1.
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
2.
Mercury (planet)
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Mercury is the smallest and innermost planet in the Solar System. Its orbital period around the Sun of 88 days is the shortest of all the planets in the Solar System and it is named after the Roman deity Mercury, the messenger to the gods. Like Venus, Mercury orbits the Sun within Earths orbit as a planet, so it can only be seen visually in the morning or the evening sky. Also, like Venus and the Moon, the displays the complete range of phases as it moves around its orbit relative to Earth. Seen from Earth, this cycle of phases reoccurs approximately every 116 days, although Mercury can appear as a bright star-like object when viewed from Earth, its proximity to the Sun often makes it more difficult to see than Venus. Mercury is tidally or gravitationally locked with the Sun in a 3,2 resonance, as seen relative to the fixed stars, it rotates on its axis exactly three times for every two revolutions it makes around the Sun. As seen from the Sun, in a frame of reference that rotates with the orbital motion, an observer on Mercury would therefore see only one day every two years. Mercurys axis has the smallest tilt of any of the Solar Systems planets, at aphelion, Mercury is about 1.5 times as far from the Sun as it is at perihelion. Mercurys surface appears heavily cratered and is similar in appearance to the Moons, the polar regions are constantly below 180 K. The planet has no natural satellites. Mercury is one of four planets in the Solar System. It is the smallest planet in the Solar System, with a radius of 2,439.7 kilometres. Mercury is also smaller—albeit more massive—than the largest natural satellites in the Solar System, Ganymede, Mercury consists of approximately 70% metallic and 30% silicate material. Mercurys density is the second highest in the Solar System at 5.427 g/cm3, Mercurys density can be used to infer details of its inner structure. Although Earths high density results appreciably from gravitational compression, particularly at the core, Mercury is much smaller, therefore, for it to have such a high density, its core must be large and rich in iron. Geologists estimate that Mercurys core occupies about 55% of its volume, Research published in 2007 suggests that Mercury has a molten core. Surrounding the core is a 500–700 km mantle consisting of silicates, based on data from the Mariner 10 mission and Earth-based observation, Mercurys crust is estimated to be 35 km thick. One distinctive feature of Mercurys surface is the presence of narrow ridges
3.
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
4.
Curiosity (rover)
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Curiosity is a car-sized robotic rover exploring Gale Crater on Mars as part of NASAs Mars Science Laboratory mission. Curiosity was launched from Cape Canaveral on November 26,2011, at 15,02 UTC aboard the MSL spacecraft, the Bradbury Landing site was less than 2.4 km from the center of the rovers touchdown target after a 560 million km journey. Curiositys design will serve as the basis for the planned Mars 2020 rover, in December 2012, Curiositys two-year mission was extended indefinitely. As of April 7,2017, Curiosity has been on Mars for 1659 sols since landing on August 6,2012, the mission will also help prepare for human exploration. This data would be important for a manned mission. The remaining mass of the MSL craft was discarded in the process of carrying out this task, dimensions, Curiosity has a mass of 899 kg including 80 kg of scientific instruments. The rover is 2.9 m long by 2.7 m wide by 2.2 m in height, power source, Curiosity is powered by a radioisotope thermoelectric generator, like the successful Viking 1 and Viking 2 Mars landers in 1976. Radioisotope power systems are generators that produce electricity from the decay of isotopes, such as plutonium-238. Heat given off by the decay of this isotope is converted into electric voltage by thermocouples, providing constant power during all seasons and through the day, waste heat can be used via pipes to warm systems, freeing electrical power for the operation of the vehicle and instruments. Curiositys RTG is fueled by 4.8 kg of plutonium-238 dioxide supplied by the U. S. Department of Energy. The MMRTG produces less power over time as its plutonium fuel decays, at its minimum lifetime of 14 years, electrical power output is down to 100 watts. The power source will generate 9 MJ each day, much more than the solar panels of the Mars Exploration Rovers, the electrical output from the MMRTG charges two rechargeable lithium-ion batteries. This enables the power subsystem to meet power demands of rover activities when the demand temporarily exceeds the generator’s steady output level. Each battery has a capacity of about 42 ampere-hours, heat rejection system, The temperatures at the landing site can vary from −127 to 40 °C, therefore, the thermal system will warm the rover for most of the Martian year. It uses fluid pumped through 60 m of tubing in the body so that sensitive components are kept at optimal temperatures. The HRS also has the ability to cool components if necessary, the computers run the VxWorks real-time operating system. Each computers memory includes 256 kB of EEPROM,256 MB of DRAM, for comparison, the Mars Exploration Rovers used 3 MB of EEPROM,128 MB of DRAM, and 256 MB of flash memory. The RCE computers use the RAD750 CPU, which is a successor to the RAD6000 CPU of the Mars Exploration Rovers
5.
Mars
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Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is referred to as the Red Planet because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet, Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan, there are ongoing investigations assessing the past habitability potential of Mars, as well as the possibility of extant life. Future astrobiology missions are planned, including the Mars 2020 and ExoMars rovers, liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is about 6⁄1000 that of the Earths, except at the lowest elevations for short periods. The two polar ice caps appear to be largely of water. The volume of ice in the south polar ice cap, if melted. On November 22,2016, NASA reported finding a large amount of ice in the Utopia Planitia region of Mars. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior, Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −2.91, which is surpassed only by Jupiter, Venus, the Moon, optical ground-based telescopes are typically limited to resolving features about 300 kilometers across when Earth and Mars are closest because of Earths atmosphere. Mars is approximately half the diameter of Earth with an area only slightly less than the total area of Earths dry land. Mars is less dense than Earth, having about 15% of Earths volume and 11% of Earths mass, the red-orange appearance of the Martian surface is caused by iron oxide, or rust. It can look like butterscotch, other common colors include golden, brown, tan. Like Earth, Mars has differentiated into a metallic core overlaid by less dense materials. Current models of its interior imply a core with a radius of about 1,794 ±65 kilometers, consisting primarily of iron and this iron sulfide core is thought to be twice as rich in lighter elements than Earths. The core is surrounded by a mantle that formed many of the tectonic and volcanic features on the planet
6.
Transit (astronomy)
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The word transit refers to cases where the nearer object appears considerably smaller than the more distant object. Cases where the object appears larger and completely hides the more distant object are known as occultations. One example of a transit involves the motion of a planet between an observer and the Sun. This can happen only with inferior planets, namely Mercury and Venus, however, as seen from outer planets such as Mars, the Earth itself transits the Sun on occasion. The term can also be used to describe the motion of a satellite across its parent planet, for one of the Galilean satellites across Jupiter. A transit requires three bodies to be lined up in a single line, more rare are cases where four bodies are lined up. The one closest to the present occurred on 27 June 1586, when Mercury transited the Sun as seen from Venus at the time as a transit of Mercury from Saturn. In recent years the discovery of planets has excited interest in the possibility of detecting their transits across their own stellar primaries. HD 209458b is the first such transiting planet to be discovered, in rare cases, one planet can pass in front of another. If the nearer planet appears smaller than the distant one. During a transit there are four contacts, when the circumference of the circle touches the circumference of the large circle at a single point. Historically, measuring the time of each point of contact was one of the most accurate ways to determine the positions of astronomical bodies. No missions were planned to coincide with the transit of Earth visible from Mars on 11 May 1984, consequently, the next opportunity to observe such an alignment will be in 2084. On December 21,2012, the Cassini–Huygens probe, in orbit around Saturn, on 3 June 2014, the Mars rover Curiosity observed the planet Mercury transiting the Sun, marking the first time a planetary transit has been observed from a celestial body besides Earth. 1989, ISBN 0-943396-25-5 Jean Meeus, Astronomical Tables of the Sun, Moon,1995, ISBN 0-943396-45-X Karl Ramsayer, Geodätische Astronomie, Vol. 2a of Handbuch der Vermessungskunde,900 p. J. B. Metzler, Stuttgart 1969
7.
Planet
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The term planet is ancient, with ties to history, astrology, science, mythology, and religion. Several planets in the Solar System can be seen with the naked eye and these were regarded by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, in 2006, the International Astronomical Union officially adopted a resolution defining planets within the Solar System. This definition is controversial because it excludes many objects of mass based on where or what they orbit. The planets were thought by Ptolemy to orbit Earth in deferent, at about the same time, by careful analysis of pre-telescopic observation data collected by Tycho Brahe, Johannes Kepler found the planets orbits were not circular but elliptical. As observational tools improved, astronomers saw that, like Earth, the planets rotated around tilted axes, and some shared such features as ice caps and seasons. Since the dawn of the Space Age, close observation by space probes has found that Earth and the planets share characteristics such as volcanism, hurricanes, tectonics. Planets are generally divided into two types, large low-density giant planets, and smaller rocky terrestrials. Under IAU definitions, there are eight planets in the Solar System, in order of increasing distance from the Sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four giant planets, Jupiter, Saturn, Uranus, and Neptune. Six of the planets are orbited by one or more natural satellites, several thousands of planets around other stars have been discovered in the Milky Way. e. in the habitable zone. On December 20,2011, the Kepler Space Telescope team reported the discovery of the first Earth-sized extrasolar planets, Kepler-20e and Kepler-20f, orbiting a Sun-like star, Kepler-20. A2012 study, analyzing gravitational microlensing data, estimates an average of at least 1.6 bound planets for every star in the Milky Way, around one in five Sun-like stars is thought to have an Earth-sized planet in its habitable zone. The idea of planets has evolved over its history, from the lights of antiquity to the earthly objects of the scientific age. The concept has expanded to include not only in the Solar System. The ambiguities inherent in defining planets have led to much scientific controversy, the five classical planets, being visible to the naked eye, have been known since ancient times and have had a significant impact on mythology, religious cosmology, and ancient astronomy. In ancient times, astronomers noted how certain lights moved across the sky, as opposed to the fixed stars, ancient Greeks called these lights πλάνητες ἀστέρες or simply πλανῆται, from which todays word planet was derived. In ancient Greece, China, Babylon, and indeed all pre-modern civilizations, it was almost universally believed that Earth was the center of the Universe and that all the planets circled Earth. The first civilization known to have a theory of the planets were the Babylonians
8.
Transit of Venus
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A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and a superior planet, becoming visible against the solar disk. During a transit, Venus can be seen from Earth as a black disk moving across the face of the Sun. The duration of such transits is usually measured in hours, a transit is similar to a solar eclipse by the Moon. While the diameter of Venus is more than 3 times that of the Moon, Venus appears smaller, Transits of Venus are among the rarest of predictable astronomical phenomena. They occur in a pattern that repeats every 243 years. The periodicity is a reflection of the fact that the periods of Earth. The last transit of Venus was on 5 and 6 June 2012, and was the last Venus transit of the 21st century, the previous pair of transits were in December 1874 and December 1882. The next transits of Venus will be on 10–11 December 2117, Venus transits are historically of great scientific importance as they were used to gain the first realistic estimates of the size of the Solar System. Observations of the 1639 transit, combined with the principle of parallax, the 2012 transit provided scientists with a number of other research opportunities, particularly in the refinement of techniques to be used in the search for exoplanets. Venus, with an orbit inclined by 3. 4° relative to the Earths, although the inclination between these two orbital planes is only 3. 4°, Venus can be as far as 9. 6° from the Sun when viewed from the Earth at inferior conjunction. Since the angular diameter of the Sun is about half a degree, sequences of transits usually repeat every 243 years. After this period of time Venus and Earth have returned to nearly the same point in their respective orbits. During the Earths 243 sidereal orbital periods, which total 88,757.3 days, Venus completes 395 sidereal orbital periods of 224.701 days each and this period of time corresponds to 152 synodic periods of Venus. Prior to 1518, the pattern of transits was 8,113.5 and 121.5 years, the current pattern will continue until 2846, when it will be replaced by a pattern of 105.5,129.5 and 8 years. Thus, the 243-year cycle is relatively stable, but the number of transits, for instance, there is a series which ended in 541 BC, and the series which includes 2117 only started in AD1631. Ancient Indian, Greek, Egyptian, Babylonian and Chinese observers knew of Venus, the early Greek astronomers called Venus by two names—Hesperus the evening star and Phosphorus the morning star. Pythagoras is credited with realizing they were the same planet, there is no evidence that any of these cultures knew of the transits. Venus was important to ancient American civilizations, in particular for the Maya, who called it Noh Ek, the Great Star or Xux Ek, the Wasp Star, they embodied Venus in the form of the god Kukulkán
9.
Mars rover
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A Mars rover is an automated motor vehicle that propels itself across the surface of the planet Mars upon arrival. There have been four successful robotically operated Mars rovers, the Jet Propulsion Laboratory managed the Mars Pathfinder mission and its now inactive Sojourner rover. It currently manages the Mars Exploration Rover missions active Opportunity rover and inactive Spirit, and, as part of the Mars Science Laboratory mission, the search for evidence of habitability, taphonomy, and organic carbon on the planet Mars is now a primary NASA objective. Several rovers have been sent to Mars, Mars 2, Prop-M rover,1971, the Mars 2 and 3 spacecraft from the USSR had identical 4.5 kg Prop-M rovers. They were to move on skis while connected to the landers with cables, Mars 3, Prop-M rover,1971, lost when Mars 3 lander stopped communicating about 20 seconds after landing. Sojourner rover, Mars Pathfinder, landed successfully on July 4,1997, communications were lost on September 27,1997. Beagle 2, Planetary Undersurface Tool, lost with Beagle 2 on deployment from Mars Express in 2003. A compressed spring mechanism was designed to allow movement across the surface at a rate of 1 cm per 5 seconds and to burrow into the ground and collect a subsurface sample in a cavity in its tip. Spirit, Mars Exploration Rover, launched on June 10,2003 at 13,58,47 EDT, nearly 6 years after the original mission limit, Spirit had covered a total distance of 7.73 km but its wheels became trapped in sand. Around January 26,2010, NASA conceded defeat in its efforts to free the rover, the last communication received from the rover was on March 22,2010, and NASA ceased attempts to re-establish communication on May 25,2011. Opportunity, Mars Exploration Rover, launched on July 7,2003 at 23,18,15 EDT, Opportunity is still operational and mobile as of April 7,2017. Curiosity, Mars Science Laboratory, by NASA, was launched November 26,2011 at 10,02 EST, Curiosity Rover is still operational as of April 7,2017. Mars rovers in development include, ExoMars, by the ESA, the rover will use stained glass to prevent UV from changing image colors, allowing for true color images of the surface of Mars. Chinese Mars Rover, has planned for a pre-2020 launch. MESR, REX, and MRPTA have a destination of Mars. Mars 2020, a NASA rover based on the current rover Curiosity,2020 Chinese Mars Mission, would include an orbiter, lander and small rover. One experimental design, not proposed for any mission, is, Mars Tumbleweed Rover. Many Mars Design Reference Mission include rovers as do some Mars sample return Astrobiology Field Laboratory, Mars Astrobiology Explorer-Cacher, cancelled 2011 Mars Surveyor 2001 rover, NASA distinguishes between mission objectives and science objectives
10.
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
11.
Solar System
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The Solar System is the gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly. Of those objects that orbit the Sun directly, the largest eight are the planets, with the remainder being significantly smaller objects, such as dwarf planets, of the objects that orbit the Sun indirectly, the moons, two are larger than the smallest planet, Mercury. The Solar System formed 4.6 billion years ago from the collapse of a giant interstellar molecular cloud. The vast majority of the mass is in the Sun. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being composed of rock. The four outer planets are giant planets, being more massive than the terrestrials. All planets have almost circular orbits that lie within a flat disc called the ecliptic. The Solar System also contains smaller objects, the asteroid belt, which lies between the orbits of Mars and Jupiter, mostly contains objects composed, like the terrestrial planets, of rock and metal. Beyond Neptunes orbit lie the Kuiper belt and scattered disc, which are populations of trans-Neptunian objects composed mostly of ices, within these populations are several dozen to possibly tens of thousands of objects large enough that they have been rounded by their own gravity. Such objects are categorized as dwarf planets, identified dwarf planets include the asteroid Ceres and the trans-Neptunian objects Pluto and Eris. In addition to two regions, various other small-body populations, including comets, centaurs and interplanetary dust clouds. Six of the planets, at least four of the dwarf planets, each of the outer planets is encircled by planetary rings of dust and other small objects. The solar wind, a stream of charged particles flowing outwards from the Sun, the heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium, it extends out to the edge of the scattered disc. The Oort cloud, which is thought to be the source for long-period comets, the Solar System is located in the Orion Arm,26,000 light-years from the center of the Milky Way. For most of history, humanity did not recognize or understand the concept of the Solar System, the invention of the telescope led to the discovery of further planets and moons. The principal component of the Solar System is the Sun, a G2 main-sequence star that contains 99. 86% of the known mass. The Suns four largest orbiting bodies, the giant planets, account for 99% of the mass, with Jupiter. The remaining objects of the Solar System together comprise less than 0. 002% of the Solar Systems total mass, most large objects in orbit around the Sun lie near the plane of Earths orbit, known as the ecliptic
12.
Orbital node
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An orbital node is one of the two points where an orbit crosses a plane of reference to which it is inclined. An orbit that is contained in the plane of reference has no nodes, common planes of reference include, For a geocentric orbit, the Earths equatorial plane. In this case, non-inclined orbits are called equatorial, for a heliocentric orbit, the ecliptic. In this case, non-inclined orbits are called ecliptic, for an orbit outside the Solar System, the plane through the primary perpendicular to a line through the observer and the primary. If a reference direction from one side of the plane of reference to the other is defined, the two nodes can be distinguished. For geocentric and heliocentric orbits, the node is where the orbiting object moves north through the plane of reference. The position of the node may be used as one of a set of parameters, called orbital elements and this is done by specifying the longitude of the ascending node The line of nodes is the intersection of the objects orbital plane with the plane of reference. It passes through the two nodes, the symbol of the ascending node is, and the symbol of the descending node is. In medieval and early times the ascending and descending nodes were called the dragons head and dragons tail. These terms originally referred to the times when the Moon crossed the apparent path of the sun in the sky, also, corruptions of the Arabic term such as ganzaar, genzahar, geuzaar and zeuzahar were used in the medieval West to denote either of the nodes. Pp. 196–197, p.65, pp. 95–96, the Greek terms αναβιβάζων and καταβιβάζων were also used for the ascending and descending nodes, giving rise to the English words anabibazon and catabibazon. For the orbit of the Moon around the Earth, the plane is taken to be the ecliptic. The gravitational pull of the Sun upon the Moon causes its nodes, called the nodes, to precess gradually westward. Eclipse Euler angles Longitude of the ascending node
13.
Pierre Gassendi
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Pierre Gassendi was a French philosopher, priest, astronomer, and mathematician. While he held a position in south-east France, he also spent much time in Paris. He was also an active observational scientist, publishing the first data on the transit of Mercury in 1631, the lunar crater Gassendi is named after him. He wrote numerous works, and some of the positions he worked out are considered significant. Richard Popkin indicates that Gassendi was one of the first thinkers to formulate the scientific outlook. He clashed with his contemporary Descartes on the possibility of certain knowledge and his best known intellectual project attempted to reconcile Epicurean atomism with Christianity. Gassendi was born at Champtercier, near Digne, in France to Antoine Gassend, a youthful prodigy, at a very early age he showed academic potential and attended the college at Digne, where he displayed a particular aptitude for languages and mathematics. Soon afterwards he entered the University of Aix-en-Provence, to study philosophy under Philibert Fesaye, in 1612 the college of Digne called him to lecture on theology. Four years later he received the degree of Doctor of Theology at Avignon, in the same year he answered a call to the chair of philosophy at Aix-en-Provence University, and seems gradually to have withdrawn from theology. He lectured principally on the Aristotelian philosophy, conforming as far as possible to the traditional methods while he followed with interest the discoveries of Galileo. He came into contact with the astronomer Joseph Gaultier de la Vallette, in 1623 the Society of Jesus took over the University of Aix. They filled all positions with Jesuits, so Gassendi was required to find another institution and he left, returning to Digne, and then travelled for the chapter to Grenoble. In 1624 he printed the first part of his Exercitationes paradoxicae adversus Aristoteleos and he spent some time with his patron Nicolas Peiresc. After 1628 Gassendi travelled in Flanders and in Holland where he encountered Isaac Beeckman and he returned to France in 1631, and two years later became provost of Digne Cathedral. During this time he wrote some works, at the insistence of Marin Mersenne and they included his examination of the mystical philosophy of Robert Fludd, an essay on parhelia, and some observations on the transit of Mercury. Gassendi then spent some years travelling through Provence with the duke of Angoulême, during this period he wrote only the one literary work, his Life of Peiresc, whose death in 1637 seemed to afflict him deeply, it received frequent reprintings and an English translation. He returned to Paris in 1641, where he met Thomas Hobbes, in 1642 Mersenne engaged him in controversy with René Descartes. His objections to the propositions of Descartes appeared in print in 1642
14.
Johannes Kepler
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Johannes Kepler was a German mathematician, astronomer, and astrologer. A key figure in the 17th-century scientific revolution, he is best known for his laws of motion, based on his works Astronomia nova, Harmonices Mundi. These works also provided one of the foundations for Isaac Newtons theory of universal gravitation, Kepler was a mathematics teacher at a seminary school in Graz, where he became an associate of Prince Hans Ulrich von Eggenberg. Later he became an assistant to the astronomer Tycho Brahe in Prague and he was also a mathematics teacher in Linz, and an adviser to General Wallenstein. Kepler lived in an era when there was no distinction between astronomy and astrology, but there was a strong division between astronomy and physics. Kepler was born on December 27, the feast day of St John the Evangelist,1571 and his grandfather, Sebald Kepler, had been Lord Mayor of the city. By the time Johannes was born, he had two brothers and one sister and the Kepler family fortune was in decline and his father, Heinrich Kepler, earned a precarious living as a mercenary, and he left the family when Johannes was five years old. He was believed to have died in the Eighty Years War in the Netherlands and his mother Katharina Guldenmann, an innkeepers daughter, was a healer and herbalist. Born prematurely, Johannes claimed to have weak and sickly as a child. Nevertheless, he often impressed travelers at his grandfathers inn with his phenomenal mathematical faculty and he was introduced to astronomy at an early age, and developed a love for it that would span his entire life. At age six, he observed the Great Comet of 1577, in 1580, at age nine, he observed another astronomical event, a lunar eclipse, recording that he remembered being called outdoors to see it and that the moon appeared quite red. However, childhood smallpox left him with vision and crippled hands. In 1589, after moving through grammar school, Latin school, there, he studied philosophy under Vitus Müller and theology under Jacob Heerbrand, who also taught Michael Maestlin while he was a student, until he became Chancellor at Tübingen in 1590. He proved himself to be a mathematician and earned a reputation as a skilful astrologer. Under the instruction of Michael Maestlin, Tübingens professor of mathematics from 1583 to 1631 and he became a Copernican at that time. In a student disputation, he defended heliocentrism from both a theoretical and theological perspective, maintaining that the Sun was the source of motive power in the universe. Despite his desire to become a minister, near the end of his studies, Kepler was recommended for a position as teacher of mathematics and he accepted the position in April 1594, at the age of 23. Keplers first major work, Mysterium Cosmographicum, was the first published defense of the Copernican system
15.
Jeremiah Horrocks
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Jeremiah Horrocks, sometimes given as Jeremiah Horrox, was an English astronomer. Jeremiah Horrocks was born at Lower Lodge Farm in Toxteth Park and his father James had moved to Toxteth Park to be apprenticed to Thomas Aspinwall, a watchmaker, and subsequently married his masters daughter Mary. Both families were well educated Puritans, the Horrocks sent their sons to the University of Cambridge. For their unorthodox beliefs the Puritans were excluded from public office, in 1632 Horrocks matriculated at Emmanuel College at the University of Cambridge as a sizar. At Cambridge he associated with the mathematician John Wallis and the platonist John Worthington, at that time he was one of only a few at Cambridge to accept Copernicuss revolutionary heliocentric theory, and he studied the works of Johannes Kepler, Tycho Brahe and others. In 1635 for reasons not clear Horrocks left Cambridge without graduating, now committed to the study of astronomy, Horrocks began to collect astronomical books and equipment, by 1638 he owned the best telescope he could find. Liverpool was a town so navigational instruments such as the astrolabe. But there was no market for the very specialised astronomical instruments he needed and he was well placed to do this, his father and uncles were watchmakers with expertise in creating precise instruments. While a youth he read most of the treatises of his day and marked their weaknesses. Tradition has it that after he left home he supported himself by holding a curacy in Much Hoole, near Preston in Lancashire, according to local tradition in Much Hoole, he lived at Carr House, within the Bank Hall Estate, Bretherton. Carr House was a property owned by the Stones family who were prosperous farmers and merchants. Horrocks was the first to demonstrate that the Moon moved in a path around the Earth. He anticipated Isaac Newton in suggesting the influence of the Sun as well as the Earth on the moons orbit, in the Principia Newton acknowledged Horrockss work in relation to his theory of lunar motion. In the final months of his life Horrocks made detailed studies of tides in attempting to explain the nature of causation of tidal movements. Keplers tables had predicted a near-miss of a transit of Venus in 1639 but, having made his own observations of Venus for years, Horrocks predicted a transit would indeed occur. Horrocks made a simple helioscope by focusing the image of the Sun through a telescope onto a plane surface, from his location in Much Hoole he calculated the transit would begin at approximately 3,00 pm on 24 November 1639, Julian calendar. The weather was cloudy but he first observed the tiny black shadow of Venus crossing the Sun at about 3,15 pm, the 1639 transit was also observed by William Crabtree from his home in Broughton near Manchester. His figure of 95 million kilometres was far from the 150 million kilometres known today and it presented Horrocks enthusiastic and romantic nature, including humorous comments and passages of original poetry
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Surat
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Surat, is a port city previously known as Suryapur. It is the capital and former princely state in the Indian state of Gujarat. It is the eighth largest city and ninth largest urban agglomeration in India, Surat is the 3rd cleanest city of India, and 4th fastest growing city of the world. Surat is famous for its food, textile, and diamonds, Surat polishes over 90 percent of the worlds rough diamond. It is the capital of the Surat district. The city is located 284 kilometres south of the capital, Gandhinagar,265 kilometres south of Ahmedabad. The city centre is located 22 km south of the Tapti River, a moat divides the older parts of the city, with their narrow streets and historical houses, from the newer suburbs. Surat had a population of 4.5 million at the 2011 census, making it the second largest city in the state of Gujarat and it is the eighth largest city and ninth largest urban agglomeration of India. Surat is the 34th-largest city by area and 4th-fastest developing cities in a study conducted by the City Mayors Foundation, the city registered an annualised GDP growth rate of 11.5 per cent over the seven fiscal years between 2001 and 2008. Surat was awarded best city by the Annual Survey of Indias City-Systems in 2013, Surat is selected as the first smart IT city in India which is being constituted by the Microsoft CityNext Initiative tied up with IT services majors Tata Consultancy Services and Wipro. The city has 2.97 million internet users which is about 65% of total population, Surat was selected in 2015 for an IBM Smarter Cities Challenge grant. Surat has been selected as one of twenty Indian cities to be developed as a city under PM Narendra Modis flagship Smart Cities Mission. Surat is mentioned in Sanskrit epic, the Mahābhārata, when Lord Krishna stopped there on his way from Mathura to Dwarka, the Parsis began to settle there in the 8th century. Local Hindu traditions state that the city was founded in the last years of the fifteenth century A. C. E. by a Brahman named Gopi, in 1512 and again in 1530 Surat was ravaged by the Portuguese Empire. In 1513, the Portuguese traveller Duarte Barbosa described Surat as an important seaport, frequented by ships from Malabar. By 1520, the name of the city was Surat, when the harbour in Cambay began to silt up toward the end of fifteenth century, Surat eclipsed Cambay as the major port of western India. At the end of the 16th century, the Portuguese were undisputed masters of the Surat sea trade, on the banks of the Tapti River, there is still a picturesque fortress that was built in 1540. In 1608, ships from the English East India Company started docking in Surat, using it as a trade, the city was made the seat of a presidency of the East India Company after the success of the embassy God of Wealth
17.
Charles II of England
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Charles II was king of England, Scotland and Ireland. He was king of Scotland from 1649 until his deposition in 1651, Charles IIs father, Charles I, was executed at Whitehall on 30 January 1649, at the climax of the English Civil War. Cromwell defeated Charles II at the Battle of Worcester on 3 September 1651, Cromwell became virtual dictator of England, Scotland and Ireland, and Charles spent the next nine years in exile in France, the Dutch Republic and the Spanish Netherlands. A political crisis followed the death of Cromwell in 1658 resulted in the restoration of the monarchy. On 29 May 1660, his 30th birthday, he was received in London to public acclaim, after 1660, all legal documents were dated as if he had succeeded his father as king in 1649. Charless English parliament enacted laws known as the Clarendon Code, designed to shore up the position of the re-established Church of England, Charles acquiesced to the Clarendon Code even though he favoured a policy of religious tolerance. The major foreign policy issue of his reign was the Second Anglo-Dutch War. In 1670, he entered into the treaty of Dover. Louis agreed to aid him in the Third Anglo-Dutch War and pay him a pension, Charles attempted to introduce religious freedom for Catholics and Protestant dissenters with his 1672 Royal Declaration of Indulgence, but the English Parliament forced him to withdraw it. In 1679, Titus Oatess revelations of a supposed Popish Plot sparked the Exclusion Crisis when it was revealed that Charless brother, the crisis saw the birth of the pro-exclusion Whig and anti-exclusion Tory parties. Charles sided with the Tories, and, following the discovery of the Rye House Plot to murder Charles and James in 1683, Charles dissolved the English Parliament in 1681, and ruled alone until his death on 6 February 1685. He was received into the Roman Catholic Church on his deathbed, Charless wife, Catherine of Braganza, bore no live children, but Charles acknowledged at least twelve illegitimate children by various mistresses. He was succeeded by his brother James, Charles II was born in St Jamess Palace on 29 May 1630. His parents were Charles I and Henrietta Maria, Charles was their second son and child. Their first son was born about a year before Charles but died within a day, England, Scotland and Ireland were respectively predominantly Anglican, Presbyterian and Roman Catholic. At birth, Charles automatically became Duke of Cornwall and Duke of Rothesay, at or around his eighth birthday, he was designated Prince of Wales, though he was never formally invested. During the 1640s, when Charles was still young, his father fought Parliamentary, by spring 1646, his father was losing the war, and Charles left England due to fears for his safety. Charles I surrendered into captivity in May 1646, at The Hague, Charles had a brief affair with Lucy Walter, who later falsely claimed that they had secretly married
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Christiaan Huygens
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Christiaan Huygens, FRS was a prominent Dutch mathematician and scientist. He is known particularly as an astronomer, physicist, probabilist and horologist, Huygens was a leading scientist of his time. His work included early telescopic studies of the rings of Saturn and the discovery of its moon Titan and he published major studies of mechanics and optics, and pioneered work on games of chance. Christiaan Huygens was born on 14 April 1629 in The Hague, into a rich and influential Dutch family, Christiaan was named after his paternal grandfather. His mother was Suzanna van Baerle and she died in 1637, shortly after the birth of Huygens sister. The couple had five children, Constantijn, Christiaan, Lodewijk, Philips, Constantijn Huygens was a diplomat and advisor to the House of Orange, and also a poet and musician. His friends included Galileo Galilei, Marin Mersenne and René Descartes, Huygens was educated at home until turning sixteen years old. He liked to play with miniatures of mills and other machines and his father gave him a liberal education, he studied languages and music, history and geography, mathematics, logic and rhetoric, but also dancing, fencing and horse riding. In 1644 Huygens had as his mathematical tutor Jan Jansz de Jonge Stampioen, Descartes was impressed by his skills in geometry. His father sent Huygens to study law and mathematics at the University of Leiden, Frans van Schooten was an academic at Leiden from 1646, and also a private tutor to Huygens and his elder brother, replacing Stampioen on the advice of Descartes. Van Schooten brought his mathematical education up to date, in introducing him to the work of Fermat on differential geometry. Constantijn Huygens was closely involved in the new College, which lasted only to 1669, Christiaan Huygens lived at the home of the jurist Johann Henryk Dauber, and had mathematics classes with the English lecturer John Pell. He completed his studies in August 1649 and he then had a stint as a diplomat on a mission with Henry, Duke of Nassau. It took him to Bentheim, then Flensburg and he took off for Denmark, visited Copenhagen and Helsingør, and hoped to cross the Øresund to visit Descartes in Stockholm. While his father Constantijn had wished his son Christiaan to be a diplomat, in political terms, the First Stadtholderless Period that began in 1650 meant that the House of Orange was not in power, removing Constantijns influence. Further, he realised that his son had no interest in such a career, Huygens generally wrote in French or Latin. While still a student at Leiden he began a correspondence with the intelligencer Mersenne. Mersenne wrote to Constantijn on his sons talent for mathematics, the letters show the early interests of Huygens in mathematics
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London
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London /ˈlʌndən/ is the capital and most populous city of England and the United Kingdom. Standing on the River Thames in the south east of the island of Great Britain and it was founded by the Romans, who named it Londinium. Londons ancient core, the City of London, largely retains its 1. 12-square-mile medieval boundaries. London is a global city in the arts, commerce, education, entertainment, fashion, finance, healthcare, media, professional services, research and development, tourism. It is crowned as the worlds largest financial centre and has the fifth- or sixth-largest metropolitan area GDP in the world, London is a world cultural capital. It is the worlds most-visited city as measured by international arrivals and has the worlds largest city airport system measured by passenger traffic, London is the worlds leading investment destination, hosting more international retailers and ultra high-net-worth individuals than any other city. Londons universities form the largest concentration of education institutes in Europe. In 2012, London became the first city to have hosted the modern Summer Olympic Games three times, London has a diverse range of people and cultures, and more than 300 languages are spoken in the region. Its estimated mid-2015 municipal population was 8,673,713, the largest of any city in the European Union, Londons urban area is the second most populous in the EU, after Paris, with 9,787,426 inhabitants at the 2011 census. The citys metropolitan area is the most populous in the EU with 13,879,757 inhabitants, the city-region therefore has a similar land area and population to that of the New York metropolitan area. London was the worlds most populous city from around 1831 to 1925, Other famous landmarks include Buckingham Palace, the London Eye, Piccadilly Circus, St Pauls Cathedral, Tower Bridge, Trafalgar Square, and The Shard. The London Underground is the oldest underground railway network in the world, the etymology of London is uncertain. It is an ancient name, found in sources from the 2nd century and it is recorded c.121 as Londinium, which points to Romano-British origin, and hand-written Roman tablets recovered in the city originating from AD 65/70-80 include the word Londinio. The earliest attempted explanation, now disregarded, is attributed to Geoffrey of Monmouth in Historia Regum Britanniae and this had it that the name originated from a supposed King Lud, who had allegedly taken over the city and named it Kaerlud. From 1898, it was accepted that the name was of Celtic origin and meant place belonging to a man called *Londinos. The ultimate difficulty lies in reconciling the Latin form Londinium with the modern Welsh Llundain, which should demand a form *lōndinion, from earlier *loundiniom. The possibility cannot be ruled out that the Welsh name was borrowed back in from English at a later date, and thus cannot be used as a basis from which to reconstruct the original name. Until 1889, the name London officially applied only to the City of London, two recent discoveries indicate probable very early settlements near the Thames in the London area
20.
Edmond Halley
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Edmond Halley, FRS was an English astronomer, geophysicist, mathematician, meteorologist, and physicist who is best known for computing the orbit of Halleys Comet. He was the second Astronomer Royal in Britain, succeeding John Flamsteed, Halley was born in Haggerston, in east London. His father, Edmond Halley Sr. came from a Derbyshire family and was a wealthy soap-maker in London, as a child, Halley was very interested in mathematics. He studied at St Pauls School, and from 1673 at The Queens College, while still an undergraduate, Halley published papers on the Solar System and sunspots. While at Oxford University, Halley was introduced to John Flamsteed, influenced by Flamsteeds project to compile a catalog of northern stars, Halley proposed to do the same for the Southern Hemisphere. In 1676, Halley visited the south Atlantic island of Saint Helena, while there he observed a transit of Mercury, and realised that a similar transit of Venus could be used to determine the absolute size of the Solar System. He returned to England in May 1678, in the following year he went to Danzig on behalf of the Royal Society to help resolve a dispute. Because astronomer Johannes Hevelius did not use a telescope, his observations had been questioned by Robert Hooke, Halley stayed with Hevelius and he observed and verified the quality of Hevelius observations. In 1679, Halley published the results from his observations on St. Helena as Catalogus Stellarum Australium which included details of 341 southern stars and these additions to contemporary star maps earned him comparison with Tycho Brahe, e. g. the southern Tycho as described by Flamsteed. Halley was awarded his M. A. degree at Oxford, in 1686, Halley published the second part of the results from his Helenian expedition, being a paper and chart on trade winds and monsoons. The symbols he used to represent trailing winds still exist in most modern day weather chart representations, in this article he identified solar heating as the cause of atmospheric motions. He also established the relationship between pressure and height above sea level. His charts were an important contribution to the field of information visualisation. Halley spent most of his time on lunar observations, but was interested in the problems of gravity. One problem that attracted his attention was the proof of Keplers laws of planetary motion, Halleys first calculations with comets were thereby for the orbit of comet Kirch, based on Flamsteeds observations in 1680-1. Although he was to calculate the orbit of the comet of 1682. They indicated a periodicity of 575 years, thus appearing in the years 531 and 1106 and it is now known to have an orbital period of circa 10,000 years. In 1691, Halley built a bell, a device in which the atmosphere was replenished by way of weighted barrels of air sent down from the surface
