1.
Rosa 'Sun Flare'
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Sun Flare is a floribunda rose cultivar that was bred in the United States in 1981 by William A. Warriner. Its scientific name is JACjem, after the company introduced the rose commercially, Jackson & Perkins Co. but is known to most by its common name. The bright yellow double flowers reach 9 cm in diameter and appear in clusters of 3 to 20 in flushes throughout the flowering season, the lemon-yellow colour hardly fades with age even in hot climates, a problem many other yellow cultivars have. The ruffled flowers develop from pointed buds and have a mild licorice fragrance, Sun Flare sometimes has rose hips. The cultivar forms a low compact bush with reddish thorns and medium to small, dark green and it reaches between 60 and 120 cm in height and an average width of 75 to 90 cm. It is winter hardy up to −23 °C and very disease resistant, Sun Flare has won several awards, including gold medals in Japan and Portland and being included into the All American Rose Selection in 1983
2.
Heliophysics
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The term heliophysics means physics of the Sun, and appears to have been used only in that sense until quite recently. In the early times, heliophysics was concerned principally with the layers of the star. Usage was extended explicitly in 1981 to its meaning, denoting the physics of the entire Sun, from center to corona. As such it was a translation from the French héliophysique. It thus became a subdiscipline of heliology, heliophysics combines several other disciplines, including solar physics, and stellar physics in general, and also several branches of nuclear physics, plasma physics and space physics. The recent extension of heliophysics is closely tied to the study of weather and the phenomena that affect it. Heliophysics is now the name of one of four divisions within NASAs Science Mission Directorate, the title was used to simplify the name of the Sun--Solar-System Connections Division. NASAs restricted use of the term heliophysics has also adopted in naming the International Heliophysical Year in 2007-2008
3.
Solar phenomena
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Solar phenomena are the natural phenomena occurring within the magnetically heated outer atmospheres in the Sun. These phenomena take many forms, including wind, radio wave flux, energy bursts such as solar flares, coronal mass ejection or solar eruptions, coronal heating. The total sum of all solar fluctuations is referred to as solar variation, the collective effect of all solar variations within the Suns gravitational field is referred to as space weather. A major weather component is the wind, a stream of plasma released from the Suns upper atmosphere. It is responsible for the aurora, natural light displays in the sky in the Arctic and Antarctic, space weather disturbances can cause solar storms on Earth, disrupting communications, as well as geomagnetic storms in Earths magnetosphere and sudden ionospheric disturbances in the ionosphere. Variations in solar intensity also affect Earths climate and these variations can explain events such as ice ages and the Great Oxygenation Event, while the Suns future expansion into a red giant will likely end life on Earth. Solar activity and related events have been recorded since the 8th century BCE. Babylonians inscribed and possibly predicted solar eclipses, while the earliest extant report of sunspots dates back to the Chinese Book of Changes, c. The first extant description of the corona was in 968, while the earliest sunspot drawing was in 1128. The invention of the telescope allowed major advances in understanding, allowing the first detailed observations in the 1600s. Solar spectroscopy began in the 1800s, from which properties of the atmosphere could be determined. Photography assisted in the study of solar prominences, granulation and spectroscopy, early in the 20th century, interest in astrophysics surged in America. A number of new observatories were built with solar telescopes around the world, the 1931 invention of the coronagraph allowed the corona to be studied in full daylight. The Sun is a located at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma and magnetic fields and it has a diameter of about 1,392,684 kilometres, around 109 times that of Earth, and its mass accounts for some 99. 86% of the total mass of the Solar System. Chemically, about three quarters of the Suns mass consists of hydrogen, while the rest is mostly helium, the remaining 1. 69% consists of heavier elements, including oxygen, carbon, neon and iron. The Sun formed about 4.567 billion years ago from the collapse of a region within a large molecular cloud. Most of the matter gathered in the center, while the rest flattened into a disk that became the balance of the Solar System. The central mass became increasingly hot and dense, eventually initiating thermonuclear fusion in its core and it is actually white, but from the Earths surface it appears yellow because of atmospheric scattering of blue light
4.
Coronal mass ejection
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A coronal mass ejection is an unusually large release of plasma and magnetic field from the solar corona. They often follow solar flares and are present during a solar prominence eruption. The plasma is released into the wind, and can be observed in coronagraph imagery. Coronal mass ejections are associated with other forms of solar activity. CMEs most often originate from active regions on the Suns surface, near solar maxima, the Sun produces about three CMEs every day, whereas near solar minima, there is about one CME every five days. Coronal mass ejections release huge quantities of matter and electromagnetic radiation into space above the Suns surface, either near the corona, or farther into the planetary system, the ejected material is a plasma consisting primarily of electrons and protons. While solar flares are very fast, CMEs are relatively slow, Coronal mass ejections are associated with enormous changes and disturbances in the coronal magnetic field. They are usually observed with a white-light coronagraph, recent scientific research has shown that the phenomenon of magnetic reconnection is closely associated with CMEs and solar flares. In magnetohydrodynamic theory, the rearrangement of magnetic field lines when two oppositely directed magnetic fields are brought together is called magnetic reconnection. Reconnection releases energy stored in the original stressed magnetic fields and these magnetic field lines can become twisted in a helical structure, with a right-hand twist or a left hand twist. On the Sun, magnetic reconnection may happen on solar arcades—a series of closely occurring loops of magnetic lines of force and these lines of force quickly reconnect into a low arcade of loops, leaving a helix of magnetic field unconnected to the rest of the arcade. The sudden release of energy during this process causes the solar flare, the helical magnetic field and the material that it contains may violently expand outwards forming a CME. This also explains why CMEs and solar flares erupt from what are known as the active regions on the Sun where magnetic fields are much stronger on average. When the magnetosphere reconnects on the nightside, it releases power on the order of terawatt scale, Solar energetic particles can cause particularly strong aurorae in large regions around Earths magnetic poles. These are also known as the Northern Lights in the hemisphere. Energetic protons released by a CME can cause an increase in the number of electrons in the ionosphere. The increase in free electrons can enhance radio wave absorption, especially within the D-region of the ionosphere, humans at high altitudes, as in airplanes or space stations, risk exposure to relatively intense cosmic rays. A typical coronal mass ejection may have any or all of three features, a cavity of low electron density, a dense core, and a bright leading edge
5.
Geomagnetic storm
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A geomagnetic storm is a temporary disturbance of the Earths magnetosphere caused by a solar wind shock wave and/or cloud of magnetic field that interacts with the Earths magnetic field. The increase in the wind pressure initially compresses the magnetosphere. The solar winds magnetic field interacts with the Earth’s magnetic field, both interactions cause an increase in plasma movement through the magnetosphere and an increase in electric current in the magnetosphere and ionosphere. During the main phase of a storm, electric current in the magnetosphere creates a magnetic force that pushes out the boundary between the magnetosphere and the solar wind. The frequency of geomagnetic storms increases and decreases with the sunspot cycle, CME driven storms are more common during the maximum of the solar cycle, while CIR driven storms are more common during the minimum of the solar cycle. Several space weather phenomena tend to be associated with or are caused by a geomagnetic storm, in 1989, a geomagnetic storm energized ground induced currents that disrupted electric power distribution throughout most of the province of Quebec and caused aurorae as far south as Texas. In 1931, Sydney Chapman and Vincenzo C. A. Ferraro wrote an article, A New Theory of Magnetic Storms and they argued that whenever the Sun emits a solar flare it also emits a plasma cloud, now known as a coronal mass ejection. This plasma will travel at a velocity such that it reaches Earth within 113 days, the cloud then compresses the Earths magnetic field and thus increases this field at the Earths surface. A geomagnetic storm is defined by changes in the Dst index, the Dst index estimates the globally averaged change of the horizontal component of the Earth’s magnetic field at the magnetic equator based on measurements from a few magnetometer stations. Dst is computed once per hour and reported in near-real-time, during quiet times, Dst is between +20 and −20 nano-Tesla. A geomagnetic storm has three phases, initial, main and recovery, the initial phase is characterized by Dst increasing by 20 to 50 nT in tens of minutes. The initial phase is referred to as a storm sudden commencement. However, not all geomagnetic storms have a phase and not all sudden increases in Dst or SYM-H are followed by a geomagnetic storm. The main phase of a storm is defined by Dst decreasing to less than −50 nT. The selection of −50 nT to define a storm is somewhat arbitrary, the minimum value during a storm will be between -50 and approximately -600 nT. The duration of the phase is typically 2–8 hours. The recovery phase is when Dst changes from its value to its quiet time value. The recovery phase may last as short as 8 hours or as long as 7 days, the size of a geomagnetic storm is classified as moderate, intense or super-storm
6.
Solar prominence
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A prominence is a large, bright, gaseous feature extending outward from the Suns surface, often in a loop shape. Prominences are anchored to the Suns surface in the photosphere, the prominence plasma is typically a hundred times more lit and denser than the coronal plasma. A prominence forms over timescales of about a day and may persist in the corona for several weeks or months, some prominences break apart and may then give rise to coronal mass ejections. Scientists are currently researching how and why prominences are formed, the red-glowing looped material is plasma, a hot gas composed of electrically charged hydrogen and helium. The prominence plasma flows along a tangled and twisted structure of magnetic fields generated by the sun’s internal dynamo, an erupting prominence occurs when such a structure becomes unstable and bursts outward, releasing the plasma. A typical prominence extends over thousands of kilometers, the largest on record was estimated at over 800,000 kilometres long – roughly the radius of the Sun. The first detailed description of a solar prominence was in 14th-century Laurentian Codex and they were described as flame-like tongues of live embers. When a prominence is viewed from a different perspective so that it is against the sun instead of against space and this formation is instead called a solar filament. It is possible for a projection to be both a filament and a prominence, some prominences are so powerful that they throw out matter from the Sun into space at speeds ranging from 600 km/s to more than 1000 km/s. Other prominences form huge loops or arching columns of glowing gases over sunspots that can reach heights of hundreds of thousands of kilometers, prominences may last for a few days or even for a few months. Coronal mass ejection Solar flare Corona Galsgaard, K. Longbottom, formation of solar prominences by flux convergence. The mass of a solar quiescent prominence
7.
Sunspot
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Sunspots are temporary phenomena on the photosphere of the Sun that appear as dark spots compared with surrounding regions. They are areas of reduced surface temperature caused by concentrations of field flux that inhibit convection. Sunspots usually appear in pairs of magnetic polarity. Their number varies according to the approximately 11-year solar cycle, individual sunspots may endure anywhere from a few days to a few months, but eventually decay. Sunspots expand and contract as they move across the surface of the Sun with sizes ranging from 16 kilometers to 160,000 kilometers in diameter, the larger variety are visible from Earth without the aid of a telescope. They may travel at speeds, or proper motions of a few hundred meters per second when they first emerge. Indicating intense magnetic activity, sunspots accompany secondary phenomena such as coronal loops, most solar flares and coronal mass ejections originate in magnetically active regions around visible sunspot groupings. Similar phenomena indirectly observed on other than the sun are commonly called starspots. Although they are at temperatures of roughly 3, 000–4,500 K, isolated from the surrounding photosphere a sunspot would be brighter than the Moon. If the stress on the tubes reaches a limit, they curl up. Convection is inhibited at the points, the energy flux from the Suns interior decreases. The Wilson effect implies that sunspots are depressions on the Suns surface, observations using the Zeeman effect show that prototypical sunspots come in pairs with opposite magnetic polarity. From cycle to cycle, the polarities of leading and trailing sunspots change from north/south to south/north, magnetic pressure should tend to remove field concentrations, causing the sunspots to disperse, but sunspot lifetimes are measured in days to weeks. Sunspot activity cycles about every eleven years, the point of highest sunspot activity during a cycle is known as solar maximum, and the point of lowest activity as solar minimum. This period is observed in most other solar activity and is linked to a variation in the solar magnetic field that changes polarity with this period. Early in the cycle, sunspots appear in the latitudes and then move towards the equator as the cycle approaches maximum. Spots from two adjacent cycles can co-exist for some time, spots from adjacent cycles can be distinguished by direction of their magnetic field. The Wolf number sunspot index counts the number of sunspots
8.
Nuclear electromagnetic pulse
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A nuclear electromagnetic pulse is a characteristic burst of electromagnetic radiation created by nuclear explosions. The resulting rapidly changing electric and magnetic fields may couple with electrical and electronic systems to produce damaging current, the specific characteristics of any particular nuclear EMP event vary according to a number of factors, the most important of which is the altitude of the detonation. The term electromagnetic pulse generally excludes optical and ionizing ranges, in military terminology, a nuclear warhead detonated hundreds of kilometers above the Earths surface is known as a high-altitude electromagnetic pulse device. The fact that a pulse is produced by a nuclear explosion was known in the earliest days of nuclear weapons testing. The magnitude of the EMP and the significance of its effects, during the first United States nuclear test on 16 July 1945, electronic equipment was shielded because Enrico Fermi expected the electromagnetic pulse. The official technical history for that first nuclear test states, All signal lines were completely shielded, in spite of this many records were lost because of spurious pickup at the time of the explosion that paralyzed the recording equipment. During British nuclear testing in 1952–1953 instrumentation failures were attributed to radioflash, the first openly reported observation of the unique aspects of high-altitude nuclear EMP occurred during the helium balloon lofted Yucca nuclear test of the Hardtack I series on 28 April 1958. In that test, the field measurements from the 1.7 kiloton weapon went off the scale of the test instruments and was estimated to be about 5 times the oscilloscope limits. The Yucca EMP was initially positive-going whereas low-altitude bursts were negative pulses, also, the polarization of the Yucca EMP signal was horizontal, whereas low-altitude nuclear EMP was vertically polarized. In spite of many differences, the unique EMP results were dismissed as a possible wave propagation anomaly. The larger scientific community aware of the significance of the EMP problem after a three-article series on nuclear EMP was published in 1981 by William J. Broad in Science. In July 1962, the US carried out the Starfish Prime test and this demonstrated that the effects of a high-altitude nuclear explosion were much larger than had been previously calculated. Starfish Prime was the first success in the series of United States high-altitude nuclear tests in 1962 known as Operation Fishbowl, subsequent tests gathered more data on the high-altitude EMP phenomenon. The EMP damage of the Starfish Prime test was quickly repaired because of the ruggedness of Hawaiis electrical and these calculations, combined with the accelerating reliance on EMP-sensitive microelectronics, heightened awareness that EMP could be a significant problem. In 1962, the Soviet Union also performed three EMP-producing nuclear tests in space over Kazakhstan, the last in the Soviet Project K nuclear tests. The geomagnetic storm–like E3 pulse from Test 184 induced a current surge in an underground power line that caused a fire in the power plant in the city of Karaganda. After the collapse of the Soviet Union, the level of damage was communicated informally to U. S. scientists. After the 1991 collapse of the Soviet Union, there was a period of a few years of cooperation between United States and Russian scientists on the HEMP phenomenon
9.
Solar Dynamics Observatory
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The Solar Dynamics Observatory is a NASA mission which has been observing the Sun since 2010. Launched on February 11,2010, the observatory is part of the Living With a Star program, the goal of the LWS program is to develop the scientific understanding necessary to effectively address those aspects of the connected Sun–Earth system directly affecting life and society. The SDO spacecraft was developed at NASAs Goddard Space Flight Center in Greenbelt, Maryland, the primary mission is scheduled to last five years and three months, with expendables expected to last for ten years. Some consider SDO to be a mission to the Solar. SDO is a 3-axis stabilized spacecraft, with two solar arrays, and two antennas, in an inclined geosynchronous orbit around Earth. Data which is collected by the craft is available as soon as possible. HMI produces data to determine the sources and mechanisms of solar variability and how the physical processes inside the Sun are related to surface magnetic field. It also produces data to enable estimates of the magnetic field for studies of variability in the extended solar atmosphere. HMI observations will enable establishing the relationships between the dynamics and magnetic activity in order to understand solar variability and its effects. HMI will take measurements of the longitudinal and vector magnetic field over the entire visible solar disk thus extending the capabilities of the SOHOs MDI instrument. The instrument incorporates physics-based models in order to further understanding of the relationship between solar EUV variations and magnetic variation changes in the Sun. The Suns output of energetic extreme ultraviolet photons is primarily what heats the Earths upper atmosphere, LMSAL designed the overall instrumentation and led its development and integration. The four telescopes providing the individual light feeds for the instrument were designed, since beginning its operational phase on 2010/05/01, AIA has operated successfully, with unprecedented EUV image quality. Photographs of the Sun in these regions of the spectrum can be seen at NASAs SDO Data-website http. Images and movies of the Sun seen on any day of the mission, including within the last half-hour, can be found at http, SDO down-links science data from its two onboard high-gain antennas, and telemetry from its two onboard omnidirectional antennas. The ground station consists of two dedicated 18-meter radio antennas in White Sands Missile Range, New Mexico, constructed specifically for SDO, Mission controllers operate the spacecraft remotely from the Mission Operations Center at NASAs Goddard Space Flight Center. The combined data rate is about 130 Mbit/s, and the craft generates approximately 1.5 terabytes of data per day, NASAs Launch Services Program at Kennedy Space Center managed the payload integration and launch. After launch, the spacecraft was placed into an orbit around the Earth with a perigee of about 2,500 kilometres. 5°
10.
Sun
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The Sun is the star at the center of the Solar System. It is a perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. It is by far the most important source of energy for life on Earth. Its diameter is about 109 times that of Earth, and its mass is about 330,000 times that of Earth, accounting for about 99. 86% of the total mass of the Solar System. About three quarters of the Suns mass consists of hydrogen, the rest is mostly helium, with smaller quantities of heavier elements, including oxygen, carbon, neon. The Sun is a G-type main-sequence star based on its spectral class and it formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into a disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core and it is thought that almost all stars form by this process. The Sun is roughly middle-aged, it has not changed dramatically for more than four billion years and it is calculated that the Sun will become sufficiently large enough to engulf the current orbits of Mercury, Venus, and probably Earth. The enormous effect of the Sun on Earth has been recognized since prehistoric times, the synodic rotation of Earth and its orbit around the Sun are the basis of the solar calendar, which is the predominant calendar in use today. The English proper name Sun developed from Old English sunne and may be related to south, all Germanic terms for the Sun stem from Proto-Germanic *sunnōn. The English weekday name Sunday stems from Old English and is ultimately a result of a Germanic interpretation of Latin dies solis, the Latin name for the Sun, Sol, is not common in general English language use, the adjectival form is the related word solar. The term sol is used by planetary astronomers to refer to the duration of a solar day on another planet. A mean Earth solar day is approximately 24 hours, whereas a mean Martian sol is 24 hours,39 minutes, and 35.244 seconds. From at least the 4th Dynasty of Ancient Egypt, the Sun was worshipped as the god Ra, portrayed as a falcon-headed divinity surmounted by the solar disk, and surrounded by a serpent. In the New Empire period, the Sun became identified with the dung beetle, in the form of the Sun disc Aten, the Sun had a brief resurgence during the Amarna Period when it again became the preeminent, if not only, divinity for the Pharaoh Akhenaton. The Sun is viewed as a goddess in Germanic paganism, Sól/Sunna, in ancient Roman culture, Sunday was the day of the Sun god. It was adopted as the Sabbath day by Christians who did not have a Jewish background, the symbol of light was a pagan device adopted by Christians, and perhaps the most important one that did not come from Jewish traditions
11.
Joule
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The joule, symbol J, is a derived unit of energy in the International System of Units. It is equal to the transferred to an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre. It is also the energy dissipated as heat when a current of one ampere passes through a resistance of one ohm for one second. It is named after the English physicist James Prescott Joule, one joule can also be defined as, The work required to move an electric charge of one coulomb through an electrical potential difference of one volt, or one coulomb volt. This relationship can be used to define the volt, the work required to produce one watt of power for one second, or one watt second. This relationship can be used to define the watt and this SI unit is named after James Prescott Joule. As with every International System of Units unit named for a person, note that degree Celsius conforms to this rule because the d is lowercase. — Based on The International System of Units, section 5.2. The CGPM has given the unit of energy the name Joule, the use of newton metres for torque and joules for energy is helpful to avoid misunderstandings and miscommunications. The distinction may be also in the fact that energy is a scalar – the dot product of a vector force. By contrast, torque is a vector – the cross product of a distance vector, torque and energy are related to one another by the equation E = τ θ, where E is energy, τ is torque, and θ is the angle swept. Since radians are dimensionless, it follows that torque and energy have the same dimensions, one joule in everyday life represents approximately, The energy required to lift a medium-size tomato 1 m vertically from the surface of the Earth. The energy released when that same tomato falls back down to the ground, the energy required to accelerate a 1 kg mass at 1 m·s−2 through a 1 m distance in space. The heat required to raise the temperature of 1 g of water by 0.24 °C, the typical energy released as heat by a person at rest every 1/60 s. The kinetic energy of a 50 kg human moving very slowly, the kinetic energy of a 56 g tennis ball moving at 6 m/s. The kinetic energy of an object with mass 1 kg moving at √2 ≈1.4 m/s, the amount of electricity required to light a 1 W LED for 1 s. Since the joule is also a watt-second and the unit for electricity sales to homes is the kW·h. For additional examples, see, Orders of magnitude The zeptojoule is equal to one sextillionth of one joule,160 zeptojoules is equivalent to one electronvolt. The nanojoule is equal to one billionth of one joule, one nanojoule is about 1/160 of the kinetic energy of a flying mosquito
12.
Energy
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In physics, energy is the property that must be transferred to an object in order to perform work on – or to heat – the object, and can be converted in form, but not created or destroyed. The SI unit of energy is the joule, which is the transferred to an object by the mechanical work of moving it a distance of 1 metre against a force of 1 newton. Mass and energy are closely related, for example, with a sensitive enough scale, one could measure an increase in mass after heating an object. Living organisms require available energy to stay alive, such as the humans get from food. Civilisation gets the energy it needs from energy resources such as fuels, nuclear fuel. The processes of Earths climate and ecosystem are driven by the radiant energy Earth receives from the sun, the total energy of a system can be subdivided and classified in various ways. It may also be convenient to distinguish gravitational energy, thermal energy, several types of energy, electric energy. Many of these overlap, for instance, thermal energy usually consists partly of kinetic. Some types of energy are a mix of both potential and kinetic energy. An example is energy which is the sum of kinetic. Whenever physical scientists discover that a phenomenon appears to violate the law of energy conservation. Heat and work are special cases in that they are not properties of systems, in general we cannot measure how much heat or work are present in an object, but rather only how much energy is transferred among objects in certain ways during the occurrence of a given process. Heat and work are measured as positive or negative depending on which side of the transfer we view them from, the distinctions between different kinds of energy is not always clear-cut. In contrast to the definition, energeia was a qualitative philosophical concept, broad enough to include ideas such as happiness. The modern analog of this property, kinetic energy, differs from vis viva only by a factor of two, in 1807, Thomas Young was possibly the first to use the term energy instead of vis viva, in its modern sense. Gustave-Gaspard Coriolis described kinetic energy in 1829 in its modern sense, the law of conservation of energy was also first postulated in the early 19th century, and applies to any isolated system. It was argued for years whether heat was a physical substance, dubbed the caloric, or merely a physical quantity. In 1845 James Prescott Joule discovered the link between mechanical work and the generation of heat and these developments led to the theory of conservation of energy, formalized largely by William Thomson as the field of thermodynamics
13.
Corona
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A corona is an aura of plasma that surrounds the sun and other stars. The Suns corona extends millions of kilometres into space and is most easily seen during a solar eclipse. The word corona is a Latin word meaning crown, from the Ancient Greek κορώνη, the high temperature of the Suns corona gives it unusual spectral features, which led some in the 19th century to suggest that it contained a previously unknown element, coronium. Instead, these features have since been explained by highly ionized iron. Bengt Edlén, following the work of Grotrian, first identified the coronal spectral lines in 1940 as transitions from low-lying metastable levels of the configuration of highly ionised metals. These high stages of ionisation indicate a temperature in excess of 1,000,000 kelvins. Light from the corona comes from three sources, from the same volume of space. The suns corona is much hotter than the surface of the Sun. The corona is 10−12 times as dense as the photosphere, the corona is separated from the photosphere by the relatively shallow chromosphere. The exact mechanism by which the corona is heated is still the subject of some debate, the outer edges of the Suns corona are constantly being transported away due to open magnetic flux and hence generating the solar wind. The corona is not always evenly distributed across the surface of the sun, during periods of quiet, the corona is more or less confined to the equatorial regions, with coronal holes covering the polar regions. However, during the Suns active periods, the corona is evenly distributed over the equatorial and polar regions, the solar cycle spans approximately 11 years, from solar minimum to the following minimum. Associated with sunspots are coronal loops, loops of magnetic flux, the magnetic flux pushes the hotter photosphere aside, exposing the cooler plasma below, thus creating the relatively dark sun spots. The astronomers usually distinguish several regions, as described below, active regions are ensembles of loop structures connecting points of opposite magnetic polarity in the photosphere, the so-called coronal loops. They generally distribute in two zones of activity, which are parallel to the solar equator, the average temperature is between two and four million kelvins, while the density goes from 109 to 1010 particle per cm3. If flares are very violent, they can also perturb the photosphere, on the contrary, quiescent prominences are large, cool dense structures which are observed as dark, snake-like Hα ribbons on the solar disc. Their temperature is about 5000–8000 K, and so they are considered as chromospheric features. In 2013, images from the High Resolution Coronal Imager revealed never-before-seen magnetic braids of plasma within the layers of these active regions
14.
Outer space
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Outer space or just space, is the void that exists between celestial bodies, including Earth. The baseline temperature, as set by the radiation from the Big Bang, is 2.7 kelvins. In most galaxies, observations provide evidence that 90% of the mass is in a form, called dark matter. Data indicates that the majority of the mass-energy in the universe is a poorly understood vacuum energy of space which astronomers label dark energy. Intergalactic space takes up most of the volume of the Universe, there is no firm boundary where outer space starts. However the Kármán line, at an altitude of 100 km above sea level, is used as the start of outer space in space treaties. The framework for international law was established by the Outer Space Treaty. This treaty precludes any claims of sovereignty and permits all states to freely explore outer space. Despite the drafting of UN resolutions for the uses of outer space. Humans began the exploration of space during the 20th century with the advent of high-altitude balloon flights. Earth orbit was first achieved by Yuri Gagarin of the Soviet Union in 1961, due to the high cost of getting into space, manned spaceflight has been limited to low Earth orbit and the Moon. Outer space represents an environment for human exploration because of the dual hazards of vacuum. Microgravity also has an effect on human physiology that causes both muscle atrophy and bone loss. In addition to health and environmental issues, the economic cost of putting objects, including humans. In 350 BCE, Greek philosopher Aristotle suggested that nature abhors a vacuum and this concept built upon a 5th-century BCE ontological argument by the Greek philosopher Parmenides, who denied the possible existence of a void in space. Based on this idea that a vacuum could not exist, in the West it was held for many centuries that space could not be empty. As late as the 17th century, the French philosopher René Descartes argued that the entirety of space must be filled, in ancient China, there were various schools of thought concerning the nature of the heavens, some of which bear a resemblance to the modern understanding. In the 2nd century, astronomer Zhang Heng became convinced that space must be infinite, extending well beyond the mechanism that supported the Sun, the surviving books of the Hsüan Yeh school said that the heavens were boundless, empty and void of substance
15.
Multi-messenger astronomy
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Astronomy is a natural science that studies celestial objects and phenomena. It applies mathematics, physics, and chemistry, in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, moons, stars, galaxies, and comets, while the phenomena include supernovae explosions, gamma ray bursts, more generally, all astronomical phenomena that originate outside Earths atmosphere are within the purview of astronomy. A related but distinct subject, physical cosmology, is concerned with the study of the Universe as a whole, Astronomy is the oldest of the natural sciences. The early civilizations in recorded history, such as the Babylonians, Greeks, Indians, Egyptians, Nubians, Iranians, Chinese, during the 20th century, the field of professional astronomy split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects, theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain the results and observations being used to confirm theoretical results. Astronomy is one of the few sciences where amateurs can play an active role, especially in the discovery. Amateur astronomers have made and contributed to many important astronomical discoveries, Astronomy means law of the stars. Astronomy should not be confused with astrology, the system which claims that human affairs are correlated with the positions of celestial objects. Although the two share a common origin, they are now entirely distinct. Generally, either the term astronomy or astrophysics may be used to refer to this subject, however, since most modern astronomical research deals with subjects related to physics, modern astronomy could actually be called astrophysics. Few fields, such as astrometry, are purely astronomy rather than also astrophysics, some titles of the leading scientific journals in this field includeThe Astronomical Journal, The Astrophysical Journal and Astronomy and Astrophysics. In early times, astronomy only comprised the observation and predictions of the motions of objects visible to the naked eye, in some locations, early cultures assembled massive artifacts that possibly had some astronomical purpose. Before tools such as the telescope were invented, early study of the stars was conducted using the naked eye, most of early astronomy actually consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, and the nature of the Sun, Moon, the Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it. This is known as the model of the Universe, or the Ptolemaic system. The Babylonians discovered that lunar eclipses recurred in a cycle known as a saros
16.
Aurora
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An aurora, sometimes referred to as a polar lights or northern lights, is a natural light display in the sky, predominantly seen in the high latitude regions. The resulting ionization and excitation of atmospheric constituents emits light of varying colour, the form of the aurora, occurring within bands around both polar regions, is also dependent on the amount of acceleration imparted to the precipitating particles. Precipitating protons generally produce optical emissions as incident hydrogen atoms after gaining electrons from the atmosphere, proton auroras are usually observed at lower latitudes. A region that currently displays an aurora is called the auroral oval, early evidence for a geomagnetic connection comes from the statistics of auroral observations. Elias Loomis, and later Hermann Fritz and S. Tromholt in more detail, day-to-day positions of the auroral ovals are posted on the internet. In northern latitudes, the effect is known as the Aurora Borealis or the Northern Lights, the former term was coined by Galileo in 1619, from the Roman goddess of the dawn and the Greek name for the north wind. The Aurora Australis is visible from southern latitudes in Antarctica, Chile, Argentina, New Zealand. A geomagnetic storm causes the auroral ovals to expand, and bring the aurora to lower latitudes and it was hardly ever seen near the geographic pole, which is about 2000 km away from the magnetic pole. The aurora can be seen best at this time, which is called magnetic midnight, Auroras also occur poleward of the auroral zone as either diffuse patches or arcs, which can be sub-visual. Auroras are occasionally seen in latitudes below the zone, when a geomagnetic storm temporarily enlarges the auroral oval. Large geomagnetic storms are most common during the peak of the sunspot cycle or during the three years after the peak. An aurora may appear overhead as a corona of rays, radiating from a distant and apparent central location, an electron spirals about a field line at an angle that is determined by its velocity vectors, parallel and perpendicular, respectively, to the local geomagnetic field vector B. This angle is known as the “pitch angle” of the particle, the distance, or radius, of the electron from the field line at any time is known as its Larmor radius. The pitch angle increases as the travels to a region of greater field strength nearer to the atmosphere. Thus it is possible for particles to return, or mirror. Other particles that do not mirror enter the atmosphere and contribute to the display over a range of altitudes. Other types of auroras have been observed from space, e. g. poleward arcs stretching sunward across the cap, the related theta aurora. These are relatively infrequent and poorly understood, there are other interesting effects such as flickering aurora, black aurora and sub-visual red arcs
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Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
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Photosphere
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The photosphere is a stars outer shell from which light is radiated. It extends into a stars surface until the plasma becomes opaque, in other words, a photosphere is the deepest region of a luminous object, usually a star, that is transparent to photons of certain wavelengths. The surface of a star is defined to have a given by the effective temperature in the Stefan–Boltzmann law. Stars, excepting neutron stars, have no solid surface, therefore, the photosphere is typically used to describe the Suns or another stars visual surface. The Sun is composed primarily of the elements hydrogen and helium, they account for 74. 9% and 23. 8% of the mass of the Sun in the photosphere. All heavier elements, called metals in astronomy, account for less than 2% of the mass, with oxygen, carbon, neon, and iron being the most abundant. The Suns photosphere has a temperature between 4,500 and 6,000 K and a density of about 2×10−4 kg/m3, each granule has a lifespan of only about eight minutes, resulting in a continually shifting boiling pattern. Grouping the typical granules are super granules up to 30,000 kilometers in diameter with lifespans of up to 24 hours and these details are too fine to see on other stars. The Suns visible atmosphere has other layers above the photosphere, the 2,000 kilometer-deep chromosphere lies just between the photosphere and the much hotter but more tenuous corona, other surface features on the photosphere are solar flares and sunspots. Animated explanation of the temperature of the Photosphere
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Chromosphere
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The chromosphere is the second of the three main layers in the Suns atmosphere and is roughly 3,000 to 5,000 kilometers deep. The chromospheres rosy red color is apparent during eclipses. The Chromosphere sits just above the photosphere and below the transition region. The layer of the chromosphere atop the photosphere is homogeneous, a forest of hairy appearing spicules rise from the homogeneous layer some of which extend 10,000 km into the corona above. The density of the chromosphere is only 10−4 times that of the photosphere, the layer beneath and this makes the chromosphere normally invisible and it can be seen only during a total eclipse, where its reddish color is revealed. The color hues are anywhere between pink and red, however, without special equipment, the chromosphere cannot normally be seen due to the overwhelming brightness of the photosphere beneath. The density of the chromosphere decreases with distance from the center of the Sun and this decreases logarithmically from 1017 particles per cubic centimeter, or approximately 2×10−4 kg/m3 to under 1. 6×10−11 kg/m3 at the outer boundary. Chromospheres have been observed also in other than the Sun. Whilst the photosphere has a line spectrum, the chromospheres spectrum is dominated by emission lines. In particular, one of its strongest lines is the Hα at a wavelength of 656.3 nm, a wavelength of 656.3 nm is in the red part of the spectrum, which causes the chromosphere to have its characteristic reddish colour. By analysing the spectrum of the chromosphere, it was found that the temperature of this layer of the atmosphere increases with increasing height in the chromosphere itself. The temperature at the top of photosphere is only about 4,400 K, while at the top of chromosphere, some 2,000 km higher and this is however the opposite of what we find in the photosphere, where the temperature drops with increasing height. It is not yet fully understood what causes the temperature of the chromosphere to paradoxically increase further from the Suns interior. However, it likely to be explained, partially or totally. Solar prominences rise up through the chromosphere from the photosphere, sometimes reaching altitudes of 150,000 km and these gigantic plumes of gas are the most spectacular of solar phenomena, aside from the less frequent solar flares. The most common feature is the presence of spicules, long fingers of luminous gas which appear like the blades of a huge field of fiery grass growing upwards from the photosphere below. Spicules rise to the top of the chromosphere and then back down again over the course of about 10 minutes. Similarly, there are horizontal wisps of gas called fibrils, which last about twice as long as spicules, images taken in typical chromospheric lines show the presence of bright cells, usually called as network, while the surrounding black regions are named internetwork
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Plasma (physics)
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Plasma is one of the four fundamental states of matter, the others being solid, liquid, and gas. Yet unlike these three states of matter, plasma does not naturally exist on the Earth under normal surface conditions, the term was first introduced by chemist Irving Langmuir in the 1920s. However, true plasma production is from the separation of these ions and electrons that produces an electric field. Based on the environmental temperature and density either partially ionised or fully ionised forms of plasma may be produced. The positive charge in ions is achieved by stripping away electrons from atomic nuclei, the number of electrons removed is related to either the increase in temperature or the local density of other ionised matter. Plasma may be the most abundant form of matter in the universe, although this is currently tentative based on the existence. Plasma is mostly associated with the Sun and stars, extending to the rarefied intracluster medium, Plasma was first identified in a Crookes tube, and so described by Sir William Crookes in 1879. The nature of the Crookes tube cathode ray matter was identified by British physicist Sir J. J. The term plasma was coined by Irving Langmuir in 1928, perhaps because the glowing discharge molds itself to the shape of the Crookes tube and we shall use the name plasma to describe this region containing balanced charges of ions and electrons. Plasma is a neutral medium of unbound positive and negative particles. Although these particles are unbound, they are not ‘free’ in the sense of not experiencing forces, in turn this governs collective behavior with many degrees of variation. The average number of particles in the Debye sphere is given by the plasma parameter, bulk interactions, The Debye screening length is short compared to the physical size of the plasma. This criterion means that interactions in the bulk of the plasma are more important than those at its edges, when this criterion is satisfied, the plasma is quasineutral. Plasma frequency, The electron plasma frequency is compared to the electron-neutral collision frequency. When this condition is valid, electrostatic interactions dominate over the processes of ordinary gas kinetics, for plasma to exist, ionization is necessary. The term plasma density by itself refers to the electron density, that is. The degree of ionization of a plasma is the proportion of atoms that have lost or gained electrons, even a partially ionized gas in which as little as 1% of the particles are ionized can have the characteristics of a plasma. The degree of ionization, α, is defined as α = n i n i + n n, where n i is the number density of ions and n n is the number density of neutral atoms
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Kelvin
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The kelvin is a unit of measure for temperature based upon an absolute scale. It is one of the seven units in the International System of Units and is assigned the unit symbol K. The kelvin is defined as the fraction 1⁄273.16 of the temperature of the triple point of water. In other words, it is defined such that the point of water is exactly 273.16 K. The Kelvin scale is named after the Belfast-born, Glasgow University engineer and physicist William Lord Kelvin, unlike the degree Fahrenheit and degree Celsius, the kelvin is not referred to or typeset as a degree. The kelvin is the unit of temperature measurement in the physical sciences, but is often used in conjunction with the Celsius degree. The definition implies that absolute zero is equivalent to −273.15 °C, Kelvin calculated that absolute zero was equivalent to −273 °C on the air thermometers of the time. This absolute scale is known today as the Kelvin thermodynamic temperature scale, when spelled out or spoken, the unit is pluralised using the same grammatical rules as for other SI units such as the volt or ohm. When reference is made to the Kelvin scale, the word kelvin—which is normally a noun—functions adjectivally to modify the noun scale and is capitalized, as with most other SI unit symbols there is a space between the numeric value and the kelvin symbol. Before the 13th CGPM in 1967–1968, the unit kelvin was called a degree and it was distinguished from the other scales with either the adjective suffix Kelvin or with absolute and its symbol was °K. The latter term, which was the official name from 1948 until 1954, was ambiguous since it could also be interpreted as referring to the Rankine scale. Before the 13th CGPM, the form was degrees absolute. The 13th CGPM changed the name to simply kelvin. Its measured value was 7002273160280000000♠0.01028 °C with an uncertainty of 60 µK, the use of SI prefixed forms of the degree Celsius to express a temperature interval has not been widely adopted. In 2005 the CIPM embarked on a program to redefine the kelvin using a more experimentally rigorous methodology, the current definition as of 2016 is unsatisfactory for temperatures below 20 K and above 7003130000000000000♠1300 K. In particular, the committee proposed redefining the kelvin such that Boltzmanns constant takes the exact value 6977138065049999999♠1. 3806505×10−23 J/K, from a scientific point of view, this will link temperature to the rest of SI and result in a stable definition that is independent of any particular substance. From a practical point of view, the redefinition will pass unnoticed, the kelvin is often used in the measure of the colour temperature of light sources. Colour temperature is based upon the principle that a black body radiator emits light whose colour depends on the temperature of the radiator, black bodies with temperatures below about 7003400000000000000♠4000 K appear reddish, whereas those above about 7003750000000000000♠7500 K appear bluish
22.
Cosmic ray
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Cosmic rays are high-energy radiation, mainly originating outside the Solar System. Upon impact with the Earths atmosphere, cosmic rays can produce showers of particles that sometimes reach the surface. Composed primarily of protons and atomic nuclei, they are of mysterious origin. Data from the Fermi space telescope have been interpreted as evidence that a significant fraction of cosmic rays originate from the supernovae explosions of stars. Active galactic nuclei probably also produce cosmic rays, the term ray is a historical accident, as cosmic rays were at first, and wrongly, thought to be mostly electromagnetic radiation. In current usage, the cosmic ray almost exclusively refers to massive particles. Massive particles – those that have rest mass – can gain additional, kinetic, mass-energy when they are moving, through this process, some particles acquire tremendously high mass-energies. These are significantly higher than the energy of even the highest-energy photons detected to date. The energy of the massless photon depends solely on frequency, not speed, at the higher end of the energy spectrum, relativistic kinetic energy is the main source of the mass-energy of cosmic rays. Hence, the highest-energy detected fermionic cosmic ray was around 3×106 times more energetic than the highest-energy detected cosmic photons, of primary cosmic rays, which originate outside of Earths atmosphere, about 99% are the nuclei of well-known atoms, and about 1% are solitary electrons. Of the nuclei, about 90% are simple protons, i. e. hydrogen nuclei, 9% are alpha particles, identical to helium nuclei, a very small fraction are stable particles of antimatter, such as positrons or antiprotons. The precise nature of this fraction is an area of active research. An active search from Earth orbit for anti-alpha particles has failed to detect them, one can show that such enormous energies might be achieved by means of the Centrifugal mechanism of acceleration in Active galactic nuclei. At 50 J, the highest-energy ultra-high-energy cosmic rays have energies comparable to the energy of a 90-kilometre-per-hour baseball. As a result of discoveries, there has been interest in investigating cosmic rays of even greater energies. Most cosmic rays, however, do not have such extreme energies, however, his paper published in Physikalische Zeitschrift was not widely accepted. In 1911 Domenico Pacini observed simultaneous variations of the rate of ionization over a lake, over the sea, Pacini concluded from the decrease of radioactivity underwater that a certain part of the ionization must be due to sources other than the radioactivity of the Earth. In 1912, Victor Hess carried three enhanced-accuracy Wulf electrometers to an altitude of 5300 meters in a balloon flight
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Electron
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The electron is a subatomic particle, symbol e− or β−, with a negative elementary electric charge. Electrons belong to the first generation of the lepton particle family, the electron has a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the include a intrinsic angular momentum of a half-integer value, expressed in units of the reduced Planck constant. As it is a fermion, no two electrons can occupy the same state, in accordance with the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of particles and waves, they can collide with other particles and can be diffracted like light. Since an electron has charge, it has an electric field. Electromagnetic fields produced from other sources will affect the motion of an electron according to the Lorentz force law, electrons radiate or absorb energy in the form of photons when they are accelerated. Laboratory instruments are capable of trapping individual electrons as well as electron plasma by the use of electromagnetic fields, special telescopes can detect electron plasma in outer space. Electrons are involved in applications such as electronics, welding, cathode ray tubes, electron microscopes, radiation therapy, lasers, gaseous ionization detectors. Interactions involving electrons with other particles are of interest in fields such as chemistry. The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms, ionization or differences in the proportions of negative electrons versus positive nuclei changes the binding energy of an atomic system. The exchange or sharing of the electrons between two or more atoms is the cause of chemical bonding. In 1838, British natural philosopher Richard Laming first hypothesized the concept of a quantity of electric charge to explain the chemical properties of atoms. Irish physicist George Johnstone Stoney named this charge electron in 1891, electrons can also participate in nuclear reactions, such as nucleosynthesis in stars, where they are known as beta particles. Electrons can be created through beta decay of isotopes and in high-energy collisions. The antiparticle of the electron is called the positron, it is identical to the electron except that it carries electrical, when an electron collides with a positron, both particles can be totally annihilated, producing gamma ray photons. The ancient Greeks noticed that amber attracted small objects when rubbed with fur, along with lightning, this phenomenon is one of humanitys earliest recorded experiences with electricity. In his 1600 treatise De Magnete, the English scientist William Gilbert coined the New Latin term electricus, both electric and electricity are derived from the Latin ēlectrum, which came from the Greek word for amber, ἤλεκτρον
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Proton
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A proton is a subatomic particle, symbol p or p+, with a positive electric charge of +1e elementary charge and mass slightly less than that of a neutron. Protons and neutrons, each with masses of one atomic mass unit, are collectively referred to as nucleons. One or more protons are present in the nucleus of every atom, the number of protons in the nucleus is the defining property of an element, and is referred to as the atomic number. Since each element has a number of protons, each element has its own unique atomic number. The word proton is Greek for first, and this name was given to the nucleus by Ernest Rutherford in 1920. In previous years, Rutherford had discovered that the nucleus could be extracted from the nuclei of nitrogen by atomic collisions. Protons were therefore a candidate to be a particle, and hence a building block of nitrogen. In the modern Standard Model of particle physics, protons are hadrons, and like neutrons, although protons were originally considered fundamental or elementary particles, they are now known to be composed of three valence quarks, two up quarks and one down quark. The rest masses of quarks contribute only about 1% of a protons mass, the remainder of a protons mass is due to quantum chromodynamics binding energy, which includes the kinetic energy of the quarks and the energy of the gluon fields that bind the quarks together. At sufficiently low temperatures, free protons will bind to electrons, however, the character of such bound protons does not change, and they remain protons. A fast proton moving through matter will slow by interactions with electrons and nuclei, the result is a protonated atom, which is a chemical compound of hydrogen. In vacuum, when electrons are present, a sufficiently slow proton may pick up a single free electron, becoming a neutral hydrogen atom. Such free hydrogen atoms tend to react chemically with other types of atoms at sufficiently low energies. When free hydrogen atoms react with other, they form neutral hydrogen molecules. Protons are spin-½ fermions and are composed of three quarks, making them baryons. Protons have an exponentially decaying positive charge distribution with a mean square radius of about 0.8 fm. Protons and neutrons are both nucleons, which may be together by the nuclear force to form atomic nuclei. The nucleus of the most common isotope of the atom is a lone proton
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Ion
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An ion is an atom or a molecule in which the total number of electrons is not equal to the total number of protons, giving the atom or molecule a net positive or negative electrical charge. Ions can be created, by chemical or physical means. In chemical terms, if an atom loses one or more electrons. If an atom gains electrons, it has a net charge and is known as an anion. Ions consisting of only a single atom are atomic or monatomic ions, because of their electric charges, cations and anions attract each other and readily form ionic compounds, such as salts. In the case of ionization of a medium, such as a gas, which are known as ion pairs are created by ion impact, and each pair consists of a free electron. The word ion comes from the Greek word ἰόν, ion, going and this term was introduced by English physicist and chemist Michael Faraday in 1834 for the then-unknown species that goes from one electrode to the other through an aqueous medium. Faraday also introduced the words anion for a charged ion. In Faradays nomenclature, cations were named because they were attracted to the cathode in a galvanic device, arrhenius explanation was that in forming a solution, the salt dissociates into Faradays ions. Arrhenius proposed that ions formed even in the absence of an electric current, ions in their gas-like state are highly reactive, and do not occur in large amounts on Earth, except in flames, lightning, electrical sparks, and other plasmas. These gas-like ions rapidly interact with ions of charge to give neutral molecules or ionic salts. These stabilized species are commonly found in the environment at low temperatures. A common example is the present in seawater, which are derived from the dissolved salts. Electrons, due to their mass and thus larger space-filling properties as matter waves, determine the size of atoms. Thus, anions are larger than the parent molecule or atom, as the excess electron repel each other, as such, in general, cations are smaller than the corresponding parent atom or molecule due to the smaller size of its electron cloud. One particular cation contains no electrons, and thus consists of a single proton - very much smaller than the parent hydrogen atom. Since the electric charge on a proton is equal in magnitude to the charge on an electron, an anion, from the Greek word ἄνω, meaning up, is an ion with more electrons than protons, giving it a net negative charge. A cation, from the Greek word κατά, meaning down, is an ion with fewer electrons than protons, there are additional names used for ions with multiple charges
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Speed of light
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The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its exact value is 299792458 metres per second, it is exact because the unit of length, the metre, is defined from this constant, according to special relativity, c is the maximum speed at which all matter and hence information in the universe can travel. It is the speed at which all particles and changes of the associated fields travel in vacuum. Such particles and waves travel at c regardless of the motion of the source or the reference frame of the observer. In the theory of relativity, c interrelates space and time, the speed at which light propagates through transparent materials, such as glass or air, is less than c, similarly, the speed of radio waves in wire cables is slower than c. The ratio between c and the speed v at which light travels in a material is called the index n of the material. In communicating with distant space probes, it can take minutes to hours for a message to get from Earth to the spacecraft, the light seen from stars left them many years ago, allowing the study of the history of the universe by looking at distant objects. The finite speed of light limits the theoretical maximum speed of computers. The speed of light can be used time of flight measurements to measure large distances to high precision. Ole Rømer first demonstrated in 1676 that light travels at a speed by studying the apparent motion of Jupiters moon Io. In 1865, James Clerk Maxwell proposed that light was an electromagnetic wave, in 1905, Albert Einstein postulated that the speed of light c with respect to any inertial frame is a constant and is independent of the motion of the light source. He explored the consequences of that postulate by deriving the theory of relativity and in doing so showed that the parameter c had relevance outside of the context of light and electromagnetism. After centuries of increasingly precise measurements, in 1975 the speed of light was known to be 299792458 m/s with a measurement uncertainty of 4 parts per billion. In 1983, the metre was redefined in the International System of Units as the distance travelled by light in vacuum in 1/299792458 of a second, as a result, the numerical value of c in metres per second is now fixed exactly by the definition of the metre. The speed of light in vacuum is usually denoted by a lowercase c, historically, the symbol V was used as an alternative symbol for the speed of light, introduced by James Clerk Maxwell in 1865. In 1856, Wilhelm Eduard Weber and Rudolf Kohlrausch had used c for a different constant later shown to equal √2 times the speed of light in vacuum, in 1894, Paul Drude redefined c with its modern meaning. Einstein used V in his original German-language papers on special relativity in 1905, but in 1907 he switched to c, sometimes c is used for the speed of waves in any material medium, and c0 for the speed of light in vacuum. This article uses c exclusively for the speed of light in vacuum, since 1983, the metre has been defined in the International System of Units as the distance light travels in vacuum in 1⁄299792458 of a second
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Electromagnetic radiation
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In physics, electromagnetic radiation refers to the waves of the electromagnetic field, propagating through space carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, light, ultraviolet, X-, classically, electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields that propagate at the speed of light through a vacuum. The oscillations of the two fields are perpendicular to other and perpendicular to the direction of energy and wave propagation. The wavefront of electromagnetic waves emitted from a point source is a sphere, the position of an electromagnetic wave within the electromagnetic spectrum can be characterized by either its frequency of oscillation or its wavelength. Electromagnetic waves are produced whenever charged particles are accelerated, and these waves can interact with other charged particles. EM waves carry energy, momentum and angular momentum away from their source particle, quanta of EM waves are called photons, whose rest mass is zero, but whose energy, or equivalent total mass, is not zero so they are still affected by gravity. Thus, EMR is sometimes referred to as the far field, in this language, the near field refers to EM fields near the charges and current that directly produced them, specifically, electromagnetic induction and electrostatic induction phenomena. In the quantum theory of electromagnetism, EMR consists of photons, quantum effects provide additional sources of EMR, such as the transition of electrons to lower energy levels in an atom and black-body radiation. The energy of a photon is quantized and is greater for photons of higher frequency. This relationship is given by Plancks equation E = hν, where E is the energy per photon, ν is the frequency of the photon, a single gamma ray photon, for example, might carry ~100,000 times the energy of a single photon of visible light. The effects of EMR upon chemical compounds and biological organisms depend both upon the power and its frequency. EMR of visible or lower frequencies is called non-ionizing radiation, because its photons do not individually have enough energy to ionize atoms or molecules, the effects of these radiations on chemical systems and living tissue are caused primarily by heating effects from the combined energy transfer of many photons. In contrast, high ultraviolet, X-rays and gamma rays are called ionizing radiation since individual photons of high frequency have enough energy to ionize molecules or break chemical bonds. These radiations have the ability to cause chemical reactions and damage living cells beyond that resulting from simple heating, Maxwell derived a wave form of the electric and magnetic equations, thus uncovering the wave-like nature of electric and magnetic fields and their symmetry. Because the speed of EM waves predicted by the wave equation coincided with the speed of light. Maxwell’s equations were confirmed by Heinrich Hertz through experiments with radio waves, according to Maxwells equations, a spatially varying electric field is always associated with a magnetic field that changes over time. Likewise, a varying magnetic field is associated with specific changes over time in the electric field. In an electromagnetic wave, the changes in the field are always accompanied by a wave in the magnetic field in one direction
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Electromagnetic spectrum
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The electromagnetic spectrum is the collective term for all known frequencies and their linked wavelengths of the known photons. The electromagnetic spectrum of an object has a different meaning, and is instead the characteristic distribution of radiation emitted or absorbed by that particular object. Visible light lies toward the end, with wavelengths from 400 to 700 nanometres. The limit for long wavelengths is the size of the universe itself, until the middle of the 20th century it was believed by most physicists that this spectrum was infinite and continuous. Nearly all types of radiation can be used for spectroscopy, to study. Other technological uses are described under electromagnetic radiation, for most of history, visible light was the only known part of the electromagnetic spectrum. The ancient Greeks recognized that light traveled in straight lines and studied some of its properties, the study of light continued, and during the 16th and 17th centuries conflicting theories regarded light as either a wave or a particle. The first discovery of electromagnetic radiation other than visible light came in 1800 and he was studying the temperature of different colors by moving a thermometer through light split by a prism. He noticed that the highest temperature was beyond red and he theorized that this temperature change was due to calorific rays that were a type of light ray that could not be seen. The next year, Johann Ritter, working at the end of the spectrum. These behaved similarly to visible light rays, but were beyond them in the spectrum. They were later renamed ultraviolet radiation, during the 1860s James Maxwell developed four partial differential equations for the electromagnetic field. Two of these equations predicted the possibility of, and behavior of, analyzing the speed of these theoretical waves, Maxwell realized that they must travel at a speed that was about the known speed of light. This startling coincidence in value led Maxwell to make the inference that light itself is a type of electromagnetic wave, maxwells equations predicted an infinite number of frequencies of electromagnetic waves, all traveling at the speed of light. This was the first indication of the existence of the electromagnetic spectrum. Maxwells predicted waves included waves at very low compared to infrared. Hertz found the waves and was able to infer that they traveled at the speed of light, Hertz also demonstrated that the new radiation could be both reflected and refracted by various dielectric media, in the same manner as light. For example, Hertz was able to focus the waves using a lens made of tree resin, in a later experiment, Hertz similarly produced and measured the properties of microwaves
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Wavelength
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In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the waves shape repeats, and thus the inverse of the spatial frequency. Wavelength is commonly designated by the Greek letter lambda, the concept can also be applied to periodic waves of non-sinusoidal shape. The term wavelength is also applied to modulated waves. Wavelength depends on the medium that a wave travels through, examples of wave-like phenomena are sound waves, light, water waves and periodic electrical signals in a conductor. A sound wave is a variation in air pressure, while in light and other electromagnetic radiation the strength of the electric, water waves are variations in the height of a body of water. In a crystal lattice vibration, atomic positions vary, wavelength is a measure of the distance between repetitions of a shape feature such as peaks, valleys, or zero-crossings, not a measure of how far any given particle moves. For example, in waves over deep water a particle near the waters surface moves in a circle of the same diameter as the wave height. The range of wavelengths or frequencies for wave phenomena is called a spectrum, the name originated with the visible light spectrum but now can be applied to the entire electromagnetic spectrum as well as to a sound spectrum or vibration spectrum. In linear media, any pattern can be described in terms of the independent propagation of sinusoidal components. The wavelength λ of a sinusoidal waveform traveling at constant speed v is given by λ = v f, in a dispersive medium, the phase speed itself depends upon the frequency of the wave, making the relationship between wavelength and frequency nonlinear. In the case of electromagnetic radiation—such as light—in free space, the speed is the speed of light. Thus the wavelength of a 100 MHz electromagnetic wave is about, the wavelength of visible light ranges from deep red, roughly 700 nm, to violet, roughly 400 nm. For sound waves in air, the speed of sound is 343 m/s, the wavelengths of sound frequencies audible to the human ear are thus between approximately 17 m and 17 mm, respectively. Note that the wavelengths in audible sound are much longer than those in visible light, a standing wave is an undulatory motion that stays in one place. A sinusoidal standing wave includes stationary points of no motion, called nodes, the upper figure shows three standing waves in a box. The walls of the box are considered to require the wave to have nodes at the walls of the box determining which wavelengths are allowed, the stationary wave can be viewed as the sum of two traveling sinusoidal waves of oppositely directed velocities. Consequently, wavelength, period, and wave velocity are related just as for a traveling wave, for example, the speed of light can be determined from observation of standing waves in a metal box containing an ideal vacuum. In that case, the k, the magnitude of k, is still in the same relationship with wavelength as shown above
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Gamma ray
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Gamma ray, denoted by the lower-case Greek letter gamma, is penetrating electromagnetic radiation of a kind arising from the radioactive decay of atomic nuclei. It consists of photons in the highest observed range of photon energy, paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays, Rutherford had previously discovered two other types of radioactive decay, which he named alpha and beta rays. Gamma rays are able to ionize atoms, and are thus biologically hazardous. The decay of a nucleus from a high energy state to a lower energy state. Natural sources of gamma rays on Earth are observed in the decay of radionuclides. There are rare terrestrial natural sources, such as lightning strikes and terrestrial gamma-ray flashes, However, a large fraction of such astronomical gamma rays are screened by Earths atmosphere and can only be detected by spacecraft. Gamma rays typically have frequencies above 10 exahertz, and therefore have energies above 100 keV and wavelengths less than 10 picometers, However, this is not a strict definition, but rather only a rule-of-thumb description for natural processes. Electromagnetic radiation from radioactive decay of nuclei is referred to as gamma rays no matter its energy. This radiation commonly has energy of a few hundred keV, in astronomy, gamma rays are defined by their energy, and no production process needs to be specified. The energies of gamma rays from astronomical sources range to over 10 TeV, a notable example is the extremely powerful bursts of high-energy radiation referred to as long duration gamma-ray bursts, of energies higher than can be produced by radioactive decay. These bursts of gamma rays are thought to be due to the collapse of stars called hypernovae, the first gamma ray source to be discovered historically was the radioactive decay process called gamma decay. In this type of decay, a nucleus emits a gamma ray almost immediately upon formation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900, However, Villard did not consider naming them as a different fundamental type. Rutherford also noted that gamma rays were not deflected by a field, another property making them unlike alpha. Gamma rays were first thought to be particles with mass, like alpha, Rutherford initially believed that they might be extremely fast beta particles, but their failure to be deflected by a magnetic field indicated that they had no charge. In 1914, gamma rays were observed to be reflected from crystal surfaces, Rutherford and his coworker Edward Andrade measured the wavelengths of gamma rays from radium, and found that they were similar to X-rays, but with shorter wavelengths and higher frequency. This was eventually recognized as giving them more energy per photon
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X-ray
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X-radiation is a form of electromagnetic radiation. Most X-rays have a wavelength ranging from 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz, X-ray wavelengths are shorter than those of UV rays and typically longer than those of gamma rays. Spelling of X-ray in the English language includes the variants x-ray, xray, X-rays with high photon energies are called hard X-rays, while those with lower energy are called soft X-rays. Due to their ability, hard X-rays are widely used to image the inside of objects, e. g. in medical radiography. The term X-ray is metonymically used to refer to an image produced using this method. Since the wavelengths of hard X-rays are similar to the size of atoms they are useful for determining crystal structures by X-ray crystallography. By contrast, soft X-rays are easily absorbed in air, the length of 600 eV X-rays in water is less than 1 micrometer. There is no consensus for a definition distinguishing between X-rays and gamma rays, one common practice is to distinguish between the two types of radiation based on their source, X-rays are emitted by electrons, while gamma rays are emitted by the atomic nucleus. This definition has problems, other processes also can generate these high-energy photons. One common alternative is to distinguish X- and gamma radiation on the basis of wavelength, with radiation shorter than some arbitrary wavelength, such as 10−11 m and this criterion assigns a photon to an unambiguous category, but is only possible if wavelength is known. Occasionally, one term or the other is used in specific contexts due to precedent, based on measurement technique. Thus, gamma-rays generated for medical and industrial uses, for radiotherapy, in the ranges of 6–20 MeV. X-ray photons carry enough energy to ionize atoms and disrupt molecular bonds and this makes it a type of ionizing radiation, and therefore harmful to living tissue. A very high radiation dose over a period of time causes radiation sickness. In medical imaging this increased risk is generally greatly outweighed by the benefits of the examination. The ionizing capability of X-rays can be utilized in treatment to kill malignant cells using radiation therapy. It is also used for material characterization using X-ray spectroscopy, hard X-rays can traverse relatively thick objects without being much absorbed or scattered. For this reason, X-rays are widely used to image the inside of visually opaque objects, the most often seen applications are in medical radiography and airport security scanners, but similar techniques are also important in industry and research
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Ultraviolet
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Ultraviolet is an electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays. UV radiation constitutes about 10% of the light output of the Sun. It is also produced by electric arcs and specialized lights, such as lamps, tanning lamps. Consequently, the effects of UV are greater than simple heating effects. Suntan, freckling and sunburn are familiar effects of over-exposure, along with risk of skin cancer. Living things on dry land would be damaged by ultraviolet radiation from the Sun if most of it were not filtered out by the Earths atmosphere. More-energetic, shorter-wavelength extreme UV below 121 nm ionizes air so strongly that it is absorbed before it reaches the ground, Ultraviolet is also responsible for the formation of bone-strengthening vitamin D in most land vertebrates, including humans. The UV spectrum thus has both beneficial and harmful to human health. Ultraviolet rays are invisible to most humans, the lens in a human eye ordinarily filters out UVB frequencies or higher, and humans lack color receptor adaptations for ultraviolet rays. Under some conditions, children and young adults can see ultraviolet down to wavelengths of about 310 nm, near-UV radiation is visible to some insects, mammals, and birds. Small birds have a fourth color receptor for ultraviolet rays, this gives birds true UV vision, reindeer use near-UV radiation to see polar bears, who are poorly visible in regular light because they blend in with the snow. UV also allows mammals to see urine trails, which is helpful for animals to find food in the wild. The males and females of some species look identical to the human eye. Ultraviolet means beyond violet, violet being the color of the highest frequencies of visible light, Ultraviolet has a higher frequency than violet light. He called them oxidizing rays to emphasize chemical reactivity and to them from heat rays. The terms chemical and heat rays were eventually dropped in favour of ultraviolet and infrared radiation, in 1878 the effect of short-wavelength light on sterilizing bacteria was discovered. By 1903 it was known the most effective wavelengths were around 250 nm, in 1960, the effect of ultraviolet radiation on DNA was established. The discovery of the ultraviolet radiation below 200 nm, named vacuum ultraviolet because it is absorbed by air, was made in 1893 by the German physicist Victor Schumann
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Ionosphere
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The ionosphere is a region of Earths upper atmosphere, from about 60 km to 1,000 km altitude, and includes the thermosphere and parts of the mesosphere and exosphere. It is ionized by radiation, plays an important part in atmospheric electricity. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth. The ionosphere is a shell of electrons and electrically charged atoms and molecules that surrounds the Earth and it owes its existence primarily to ultraviolet radiation from the Sun. The lowest part of the Earths atmosphere, the troposphere extends from the surface to about 10 km, above 10 km is the stratosphere, followed by the mesosphere. In the stratosphere incoming solar radiation creates the ozone layer, at heights of above 80 km, in the thermosphere, the atmosphere is so thin that free electrons can exist for short periods of time before they are captured by a nearby positive ion. The number of free electrons is sufficient to affect radio propagation. This portion of the atmosphere is ionized and contains a plasma which is referred to as the ionosphere, in this process the light electron obtains a high velocity so that the temperature of the created electronic gas is much higher than the one of ions and neutrals. The reverse process to ionization is recombination, in which an electron is captured by a positive ion. Recombination occurs spontaneously, and causes the emission of a photon carrying away the energy produced upon recombination, as gas density increases at lower altitudes, the recombination process prevails, since the gas molecules and ions are closer together. The balance between two processes determines the quantity of ionization present. Ionization depends primarily on the Sun and its activity, the amount of ionization in the ionosphere varies greatly with the amount of radiation received from the Sun. Thus there is an effect and a seasonal effect. The local winter hemisphere is tipped away from the Sun, thus there is less received solar radiation, the activity of the Sun is associated with the sunspot cycle, with more radiation occurring with more sunspots. Radiation received also varies with geographical location, there are also mechanisms that disturb the ionosphere and decrease the ionization. There are disturbances such as flares and the associated release of charged particles into the solar wind which reaches the Earth. At night the F layer is the layer of significant ionization present. During the day, the D and E layers become more heavily ionized, as does the F layer
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Richard Christopher Carrington
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Carrington was born at Chelsea, the second son of Richard Carrington, the proprietor of a large brewery at Brentford, and his wife Esther Clarke Aplin. He entered upon his duties there in October 1849, but soon became dissatisfied with their narrow scope, the observatory was ill supplied with instruments, and the leisure left him for study served only to widen his aims. Bessels and Argelanders star-zones, above all, struck him as a model for imitation and he had not, however, been idle. His admission as a member of the Royal Astronomical Society,14 March 1851, in June 1852 he fixed upon a site for an observatory and dwelling-house at Redhill, Surrey. In July 1853 a transit-circle of 5½ feet focus, reduced in scale from the Greenwich model, and an equatoreal of 4½ inches aperture, both by Simms, were in their places, and work was begun. It included a comparison of Schwerds places for 680 stars with those obtained at Redhill. Ten corresponding maps, copper-engraved, accompanied the catalogue, meanwhile, Carrington had adopted, and was cultivating with his usual felicity of treatment, a ‘second subject’ at that juncture of peculiar interest and importance. He accordingly resolved to devote his energies to the sun. Solar physics as a whole, however, he excluded from his field of view. He limited his task to fixing the period of the suns rotation, to tracing the laws of distribution of maculæ. Adequately to compass these ends, new devices of observation, reduction, leaving photography to his successors as too undeveloped for immediate use, he chose a method founded on the idea of making the solar disc its own circular micrometer. An image of the sun was thrown upon a screen placed at such a distance from the eyepiece of the 4½-inch equatoreal as to give to the disc a diameter of 12 to 14 inches. In the focus of the telescope, which was firmly clamped, in this manner, during seven and a half years,5,290 observations were made of 954 separate groups, many of which were besides accurately depicted in drawings. The results appeared in a 4to volume, the publication of which was aided by a grant from the Royal Society and its title ran as follows, ‘Observations of the Spots on the Sun from November 9,1853, to March 24,1861, made at Redhill’. Never were data more opportunely furnished, perhaps more effectually than the pronouncements of spectrum analysis, they served to revolutionise ideas on solar physics. Efforts to ascertain the true rate of solar rotation had been baffled by what were called the ‘proper motions’ of the spots serving as indexes to it. Carrington showed that these were in reality due to a great ‘bodily drift’ of the photosphere, there was, then, no single period ascertainable through observations of the solar surface. By equatorial spots the circuit was found to be performed in two and a half days less than by spots at the extreme north and south limits of 45°
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Solar cycle
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The solar cycle or solar magnetic activity cycle is the nearly periodic 11-year change in the Suns activity and appearance. They have been observed for centuries, the changes on the sun cause effects in space, in the atmosphere, and on Earths surface. While it is the dominant variable in solar activity, aperiodic fluctuations also occur, Solar cycles have an average duration of about 11 years. Solar maximum and solar minimum refer respectively to periods of maximum and minimum sunspot counts, cycles span from one minimum to the next. The solar cycle was discovered in 1843 by Samuel Heinrich Schwabe, following Wolfs numbering scheme, the 1755–1766 cycle is traditionally numbered 1. Wolf created a standard sunspot number index, the Wolf index, the period between 1645 and 1715, a time of few sunspots, is known as the Maunder minimum, after Edward Walter Maunder, who extensively researched this peculiar event, first noted by Gustav Spörer. In the second half of the nineteenth century Richard Carrington and by Spörer independently noted the phenomena of sunspots appearing at different latitudes at different parts of the cycle, the cycles physical basis was elucidated by Hale and collaborators, who in 1908 showed that sunspots were strongly magnetized. In 1919 they showed that the polarity of sunspot pairs, Is constant throughout a cycle, Is opposite across the equator throughout a cycle. Hales observations revealed that the complete magnetic cycle spans two solar cycles, or 22 years, before returning to its original state, however, because nearly all manifestations are insensitive to polarity, the 11-year solar cycle remains the focus of research. In 1961 the father-and-son team of Harold and Horace Babcock established that the cycle is a spatiotemporal magnetic process unfolding over the Sun as a whole. Horaces Babcock model described the Suns oscillatory magnetic field, with a periodicity of 22 years. It covered the exchange of energy between poloidal and toroidal solar magnetic field ingredients. The level of activity beginning in the 1940s is exceptional – the last period of similar magnitude occurred around 9,000 years ago. The Sun was at a high level of magnetic activity for only ~10% of the past 11,400 years. Almost all earlier high-activity periods were shorter than the present episode, fossil records suggest that the Solar cycle has been stable for at least the last 290 million years. For example, the cycle length during the early Permian is estimated to be 10.62 years, since observations began, cycles have ranged from 9–14 years. The current solar cycle began on January 4,2008, with minimal activity until early 2010 and it is on track to have the lowest recorded sunspot activity since accurate records began in 1750. The cycle featured a double-peaked solar maximum, the first peak reached 99 in 2011 and the second in early 2014 at 101
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Solar storm of 2012
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The solar storm of 2012 was an unusually large and strong coronal mass ejection event that occurred on July 23 that year. It missed the Earth with a margin of nine days. The region that produced the outburst was not pointed directly towards the Earth at that time. The strength of the eruption was comparable to the 1859 Carrington event that caused damage to electric equipment worldwide, the eruption tore through Earths orbit, hitting the STEREO-A spacecraft. Had the CME hit the Earth, it is likely that it would have inflicted serious damage to systems on a global scale. A2013 study estimated that the economic cost to the United States would have been between $0.6 -2.6 trillion USD. Ying D. Liu, professor at China’s State Key Laboratory of Space Weather, the event occurred at a time of high sunspot activity during Solar cycle 24. List of solar storms ScienceCasts, Carrington-class CME Narrowly Misses Earth on YouTube
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Electronvolt
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In physics, the electronvolt is a unit of energy equal to approximately 1. 6×10−19 joules. By definition, it is the amount of energy gained by the charge of an electron moving across an electric potential difference of one volt. Thus it is 1 volt multiplied by the elementary charge, therefore, one electronvolt is equal to 6981160217662079999♠1. 6021766208×10−19 J. The electronvolt is not a SI unit, and its definition is empirical, like the elementary charge on which it is based, it is not an independent quantity but is equal to 1 J/C √2hα / μ0c0. It is a unit of energy within physics, widely used in solid state, atomic, nuclear. It is commonly used with the metric prefixes milli-, kilo-, in some older documents, and in the name Bevatron, the symbol BeV is used, which stands for billion electronvolts, it is equivalent to the GeV. By mass–energy equivalence, the electronvolt is also a unit of mass and it is common in particle physics, where units of mass and energy are often interchanged, to express mass in units of eV/c2, where c is the speed of light in vacuum. It is common to express mass in terms of eV as a unit of mass. The mass equivalent of 1 eV/c2 is 1 eV / c 2 = ⋅1 V2 =1.783 ×10 −36 kg. For example, an electron and a positron, each with a mass of 0.511 MeV/c2, the proton has a mass of 0.938 GeV/c2. In general, the masses of all hadrons are of the order of 1 GeV/c2, the unified atomic mass unit,1 gram divided by Avogadros number, is almost the mass of a hydrogen atom, which is mostly the mass of the proton. To convert to megaelectronvolts, use the formula,1 u =931.4941 MeV/c2 =0.9314941 GeV/c2, in high-energy physics, the electronvolt is often used as a unit of momentum. A potential difference of 1 volt causes an electron to gain an amount of energy and this gives rise to usage of eV as units of momentum, for the energy supplied results in acceleration of the particle. The dimensions of units are LMT−1. The dimensions of units are L2MT−2. Then, dividing the units of energy by a constant that has units of velocity. In the field of particle physics, the fundamental velocity unit is the speed of light in vacuum c. Thus, dividing energy in eV by the speed of light, the fundamental velocity constant c is often dropped from the units of momentum by way of defining units of length such that the value of c is unity
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Picometre
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The picometre or picometer is a unit of length in the metric system, equal to 1×10−12 m, or one trillionth of a metre, which is the SI base unit of length. The picometre is one thousandth of a nanometre, one millionth of a micrometre, the symbol µµ was once used for it. It is also one hundredth of an angstrom, a recognised unit of length. The picometres length is of an such that its application is almost entirely confined to particle physics, quantum physics, chemistry. Atoms are between 62 and 520 pm in diameter, and the length of a carbon-carbon single bond is 154 pm. Smaller units still may be used to describe smaller particles, such as hadrons and the upper limits of possible size for fermion point particles
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Geostationary Operational Environmental Satellite
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Spacecraft and ground-based elements of the system work together to provide a continuous stream of environmental data. The GOES system uses geosynchronous satellites which—since the launch of SMS-1 in 1974—have been an element of U. S. weather monitoring and forecasting. GOES data can be accessed using the SPEDAS software, three GOES satellites are currently available for operational use, GOES13 is designated GOES-East, currently located at 75°W. It was placed in orbit on 24 May 2006, underwent Post-Launch Testing through early 2007, GOES14 is currently in storage at 90°W. It was temporarily designated GOES-East due to difficulties with GOES-13, and moved toward the GOES-East location. Several GOES satellites are still in orbit, either inactive or re-purposed, GOES-3 is no longer used for weather operations, but is a critical part of the communication links between the United States and Amundsen–Scott South Pole Station. Geostationary satellites cannot ordinarily be seen at all from the poles, when station-keeping fuel is depleted, solar and lunar perturbations increase the satellites inclination so that its ground track begins to describe an analemma. This usually ends the satellites primary mission, but when the inclination is high enough, the satellite may begin to rise above the polar horizons at the extremes of the figure-8, as is the case for GOES-3. A nine-meter dish was constructed at the station, and communication with the satellite is currently possible for five hours per day. Data rates are around 2.048 Mbit/s bi-directional under optimum conditions, gOES-8 is in a parking orbit, currently drifting about 4°W daily. It was decommissioned on April 1,2003, and deactivated on May 5,2004, Weather data was lost for 13 days from GOES-12 on December 4,2007 when it performed a standard station-keeping maneuver. GOES-11 initially took full disk images to cover the lost data until a plan could be implemented. On December 5,2007, GOES-10 was moved from South America operations to temporarily replace GOES-12 as the GOES-EAST operational satellite, on 9 December, communication with GOES-10 was also temporarily lost, but communication was resumed via a backup antenna. GOES-12 was successfully reactivated and moved back to operation following a thrust maneuver on 17 December. The trouble was traced to a leaking thruster valve, which pushed the satellite incorrectly, emergency procedures were executed to cut off the valve, and a redundant thruster was activated to restore the location of the satellite. GOES-10 was decommissioned on December 2,2009 and was boosted to a graveyard orbit and it no longer had the fuel for required maneuvers to keep it on station. It joins GOES8 and 9 which are already in graveyard orbits, with the cessation of GOES-10s duties, GOES-13 has replaced GOES-12 as GOES-East. GOES-12 was then moved to 60° W and resume South American duties for GOES-10, gOES-11 had a partial failure 6 Dec 2011, was decommissioned on 16 Dec 2011 and was boosted into a graveyard orbit
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H-alpha
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H-alpha is a specific deep-red visible spectral line in the Balmer series with a wavelength of 656.28 nm, it occurs when a hydrogen electron falls from its third to second lowest energy level. H-alpha light is important to astronomers as it is emitted by many emission nebulae and can be used to observe features in the Suns atmosphere, according to the Bohr model of the atom, electrons exist in quantized energy levels surrounding the atoms nucleus. These energy levels are described by the quantum number n =1,2,3. Electrons may only exist in these states, and may only transit between these states, for the Lyman series the naming convention is, n =2 to n =1 is called Lyman-alpha, n =3 to n =1 is called Lyman-beta, etc. H-alpha has a wavelength of 656.281 nm, is visible in the red part of the electromagnetic spectrum, instead, after being ionized, the electron and proton recombine to form a new hydrogen atom. In the new atom, the electron may begin in any energy level, approximately half the time, this cascade will include the n =3 to n =2 transition and the atom will emit H-alpha light. Therefore, the H-alpha line occurs where hydrogen is being ionized, instead, molecules such as carbon dioxide, carbon monoxide, formaldehyde, ammonia, or acetonitrile are typically used to determine the mass of a cloud. A hydrogen-alpha filter is a filter designed to transmit a narrow bandwidth of light generally centred on the H-alpha wavelength. They are characterized by a width that measures the width of the wavelength band that is transmitted. These filters can be dichroic filters manufactured by multiple vacuum-deposited layers and these layers are selected to produce interference effects that filter out any wavelengths except at the requisite band. Taken in isolation, H-alpha dichroic filters are useful in astrophotography and they do not have narrow enough bandwidth for observing the suns atmosphere. This combination will pass only a range of wavelengths of light centred on the H-alpha emission line. The physics of the etalon and the dichroic interference filters are essentially the same, due to the high velocities sometimes associated with features visible in H-alpha light, solar H-alpha etalons can often be tuned to cope with the associated Doppler effect. Commercially available H-alpha filters for amateur solar observing usually state bandwidths in Angstrom units and are typically 0. 7Å, by using a second etalon, this can be reduced to 0. 5Å leading to improved contrast in details observed on the suns disc. An even more narrow band filter can be using a Lyot filter. Hydrogen spectral series Rydberg formula Spectrohelioscope Description of etalon filter by Colin Kaminski
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Space weather
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Space weather is distinct from the terrestrial weather of the Earths atmosphere. The science of space weather is focused on research and practical applications. The term space weather was first used in the 1950s and came into usage in the 1990s. For many centuries, the effects of weather were noticed. Displays of auroral light have long been observed at high latitudes, in 1724, George Graham reported that the needle of a magnetic compass was regularly deflected from magnetic north over the course of each day. In 1859, a magnetic storm caused brilliant auroral displays. Kristian Birkeland explained the physics of aurora by creating artificial aurora in his laboratory, the introduction of radio revealed that periods of extreme static or noise occurred. Severe radar jamming during a large event in 1942 led to the discovery of solar radio bursts. In the 20th century the interest in space weather expanded as military, communications satellites are a vital part of global commerce. Weather satellite systems provide information about terrestrial weather, the signals from satellites of the Global Positioning System are used in a wide variety of applications. Space weather phenomena can interfere with or damage these satellites or interfere with the signals with which they operate. Space weather phenomena can cause damaging surges in long distance transmission lines and expose passengers and crew of aircraft travel to radiation, the International Geophysical Year, increased research into space weather. In 1958, the Explorer I satellite discovered the Van Allen belts, in January 1959, the Soviet satellite Luna 1 first directly observed the solar wind and measured its strength. In 1969, INJUN-5 made the first direct observation of the electric field impressed on the Earths high latitude ionosphere by the solar wind, in the early 1970s, Triad data demonstrated that permanent electric currents flowed between the auroral oval and the magnetosphere. The term space weather came into usage in the 1990s along with the belief that spaces impact on human systems demanded a more coordinated research and application framework. The concept was turned into a plan in 2000, an implementation plan in 2002, an assessment in 2006. A revised action plan was scheduled to be released in 2011 followed by an implementation plan in 2012. One part of the National Space Weather Program is to show users that space weather affects their business, private companies now acknowledge space weather is a real risk for todays businesses
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Solar wind
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The solar wind is a stream of charged particles released from the upper atmosphere of the Sun. This plasma consists of electrons, protons and alpha particles with thermal energies between 1.5 and 10 keV. Embedded within the plasma is the interplanetary magnetic field. The solar wind varies in density, temperature and speed over time and its particles can escape the Suns gravity because of their high energy resulting from the high temperature of the corona, which in turn is a result of the coronal magnetic field. At a distance of more than a few radii from the sun. The flow of the wind is no longer supersonic at the termination shock. The Voyager 2 spacecraft crossed the shock more than five times between 30 August and 10 December 2007, Voyager 2 crossed the shock about a billion kilometers closer to the Sun than the 13.5 billion kilometer distance where Voyager 1 came upon the termination shock. The spacecraft moved outward through the shock into the heliosheath. Other related phenomena include the aurora, the tails of comets that always point away from the Sun. The existence of flowing outward from the Sun to the Earth was first suggested by British astronomer Richard C. In 1859, Carrington and Richard Hodgson independently made the first observation of what would later be called a solar flare, george FitzGerald later suggested that matter was being regularly accelerated away from the Sun and was reaching the Earth after several days. In 1910 British astrophysicist Arthur Eddington essentially suggested the existence of the wind, without naming it. The idea never caught on even though Eddington had also made a similar suggestion at a Royal Institution address the previous year. In the latter case, he postulated that the material consisted of electrons while in his study of Comet Morehouse he supposed them to be ions. The first person to suggest that the material consisted of both ions and electrons was Kristian Birkeland. His geomagnetic surveys showed that activity was nearly uninterrupted. In 1916, Birkeland proposed that, From a physical point of view it is most probable that solar rays are neither exclusively negative nor positive rays, in other words, the solar wind consists of both negative electrons and positive ions. Three years later in 1919, Frederick Lindemann also suggested that particles of both polarities, protons as well as electrons, come from the Sun
43.
Stellar wind
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A stellar wind is a flow of gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of stars by being less collimated. Different types of stars have different types of stellar winds, post-main-sequence stars nearing the ends of their lives often eject large quantities of mass in massive, slow winds. These include red giants and supergiants, and asymptotic giant branch stars and these winds are understood to be driven by radiation pressure on dust condensing in the upper atmosphere of the stars. Massive stars of types O and B have stellar winds with lower mass loss rates, such winds are driven by radiation pressure on the resonance absorption lines of heavy elements such as carbon and nitrogen. These high-energy stellar winds blow stellar wind bubbles, g-type stars like the Earths Sun have a wind driven by their hot, magnetized corona. The Suns wind is called the solar wind and these winds consist mostly of high-energy electrons and protons that are able to escape the stars gravity because of the high temperature of the corona. Stellar winds from main-sequence stars do not strongly influence the evolution of lower mass stars such as the Sun, solar wind Cosmic ray Cosmic wind
44.
Magnetosphere
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A magnetosphere is the region of space surrounding an astronomical object in which charged particles are controlled by that objects magnetic field. The magnetic field near the surface of many astronomical objects resembles that of a dipole, the field lines farther away from the surface can be significantly distorted by the flow of electrically conducting plasma emitted from a nearby star. Study of Earths magnetosphere began in 1600, when William Gilbert discovered that the field on the surface of Earth resembled that on a terrella. In the 1940s, Walter M. Elsasser proposed the model of dynamo theory, through the use of magnetometers, scientists were able to study the variations in Earths magnetic field as functions of both time and latitude and longitude. Beginning in the late 1940s, rockets were used to study cosmic rays, in 1958, Explorer 1, the first of the Explorer series of space missions, was launched to study the intensity of cosmic rays above the atmosphere and measure the fluctuations in this activity. This mission observed the existence of the Van Allen radiation belt, also in 1958, Eugene Parker proposed the idea of the solar wind. The term magnetosphere was proposed by Thomas Gold in 1959, the Explorer 12 mission led to the observation by Cahill and Amazeen in 1963 of a sudden decrease in the strength of the magnetic field near the noon meridian, later named the magnetopause. In 1983, the International Cometary Explorer observed the magnetotail, or the distant magnetic field, the distance at which a planet can withstand the solar wind pressure is called the Chapman–Ferraro distance. Mercury, Earth, Jupiter, Ganymede, Saturn, Uranus, a magnetosphere is classified as induced when R C F ≪ R P, or when the solar wind is not opposed by the objects magnetic field. In this case, the solar wind interacts with the atmosphere or ionosphere of the planet, when R C F ≈ R P, the planet itself and its magnetic field both contribute. It is possible that Mars is of this type, the bow shock forms the outermost layer of the magnetosphere, the boundary between the magnetosphere and the ambient medium. For stars, this is usually the boundary between the wind and interstellar medium, for planets, the speed of the solar wind there decreases as it approaches the magnetopause. The magnetosheath is the region of the magnetosphere between the bow shock and the magnetopause and it is formed mainly from shocked solar wind, though it contains a small amount of plasma from the magnetosphere. It is an area exhibiting high particle flux, where the direction. This is caused by the collection of solar wind gas that has effectively undergone thermalization and it acts as a cushion that transmits the pressure from the flow of the solar wind and the barrier of the magnetic field from the object. The magnetopause is the area of the magnetosphere wherein the pressure from the magnetic field is balanced with the pressure from the solar wind. It is the convergence of the solar wind from the magnetosheath with the magnetic field of the object. Because both sides of this convergence contain magnetized plasma, the interactions between them are complex, the structure of the magnetopause depends upon the Mach number and beta of the plasma, as well as the magnetic field
45.
Radiation
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In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. Radiation is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles, Ionizing radiation carries more than 10 eV, which is enough to ionize atoms and molecules, and break chemical bonds. This is an important distinction due to the difference in harmfulness to living organisms. A common source of ionizing radiation is radioactive materials that emit α, β, or γ radiation, consisting of helium nuclei, electrons or positrons, gamma rays, X-rays and the higher energy range of ultraviolet light constitute the ionizing part of the electromagnetic spectrum. The lower-energy, longer-wavelength part of the spectrum including visible light, infrared light, microwaves and this type of radiation only damages cells if the intensity is high enough to cause excessive heating. Ultraviolet radiation has some features of both ionizing and non-ionizing radiation and these properties derive from ultraviolets power to alter chemical bonds, even without having quite enough energy to ionize atoms. The word radiation arises from the phenomenon of waves radiating from a source and this aspect leads to a system of measurements and physical units that are applicable to all types of radiation. This law does not apply close to a source of radiation or for focused beams. Radiation with sufficiently high energy can ionize atoms, that is to say it can knock electrons off atoms, ionization occurs when an electron is stripped from an electron shell of the atom, which leaves the atom with a net positive charge. Because living cells and, more importantly, the DNA in those cells can be damaged by this ionization, thus ionizing radiation is somewhat artificially separated from particle radiation and electromagnetic radiation, simply due to its great potential for biological damage. While an individual cell is made of trillions of atoms, only a fraction of those will be ionized at low to moderate radiation powers. If the source of the radiation is a radioactive material or a nuclear process such as fission or fusion. Particle radiation is subatomic particles accelerated to relativistic speeds by nuclear reactions, because of their momenta they are quite capable of knocking out electrons and ionizing materials, but since most have an electrical charge, they dont have the penetrating power of ionizing radiation. The exception is neutron particles, see below, there are several different kinds of these particles, but the majority are alpha particles, beta particles, neutrons, and protons. Roughly speaking, photons and particles with energies above about 10 electron volts are ionizing, particle radiation from radioactive material or cosmic rays almost invariably carries enough energy to be ionizing. The radiation is invisible and not directly detectable by human senses, as a result, in some cases, it may lead to secondary emission of visible light upon its interaction with matter, as in the case of Cherenkov radiation and radio-luminescence. Ionizing radiation has many uses in medicine, research and construction. Ultraviolet, of wavelengths from 10 nm to 125 nm, ionizes air molecules, causing it to be absorbed by air
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March 1989 geomagnetic storm
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A severe geomagnetic storm struck Earth on March 13,1989. It occurred during solar cycle 22 and caused an outage of Hydro-Québecs electricity transmission system. The geomagnetic storm causing this event was itself the result of a coronal mass ejection on March 9,1989, a few days before, on March 6, a very large X15-class solar flare also occurred. Three and a half later, at 2,44 am EST on March 13. The storm began on Earth with extremely intense auroras at the poles, the aurora could be seen as far south as Texas and Florida. As this occurred during the Cold War, a number of people worried that a nuclear first strike might be in progress. Others incorrectly considered the intense auroras to be associated with the Space Shuttle mission STS-29, the burst caused short-wave radio interference, including the disruption of radio signals from Radio Free Europe into Russia. It was initially believed that the signals had been jammed by the Soviet government, some satellites in polar orbits lost control for several hours. GOES weather satellite communications were interrupted, causing weather images to be lost, nASAs TDRS-1 communication satellite recorded over 250 anomalies caused by the increased particles flowing into its sensitive electronics. The Space Shuttle Discovery was having its own problems, a sensor on one of the tanks supplying hydrogen to a cell was showing unusually high pressure readings on March 13. The problem went away after the storm subsided. The variations in the magnetic field also tripped circuit breakers on Hydro-Québecs power grid. The James Bay network went offline in less than 90 seconds, other utilities in North America and Northern Europe and elsewhere implemented programs to reduce the risks associated with geomagnetically induced currents. One of the few publicly reported military operations impacted was the Australian Army component of the United Nations peacekeeping force which was deployed to Namibia at the time. The storm occurred just as the elements of the contingent arrived in Namibia. The Australian contribution to UNTAG was heavily reliant on HF radio communications which were severely impacted, in August 1989, another storm caused a halt of all trading on Torontos stock market. Since 1995, geomagnetic storms and solar flares have been monitored from the Solar and Heliospheric Observatory satellite, a joint project of NASA and the European Space Agency
. Bibcode:2004ApJ...609.1134W. doi:10.1086/421261.
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