1.
22 Kalliope
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22 Kalliope is a large M-type asteroid from the asteroid belt discovered by J. R. Hind on November 16,1852. It is named after Calliope, the Greek Muse of epic poetry and it is orbited by a small moon named Linus. Kalliope is somewhat elongated, approximately 166 km in diameter, and slightly asymmetric and this new diameter, which was measured by observing mutual eclipses of Kalliope and Linus, is 8% smaller than that calculated from IRAS observations. The spectrum of Kalliope is an M-type, indicating that its surface may be composed of iron–nickel metal. The asteroids density is about 3.4 g/cm3, spectroscopic studies have shown, however, evidence of hydrated minerals and silicates, which indicate rather a stony surface composition. Kalliope also has a low albedo, which is inconsistent with a purely metallic surface. Lightcurve analysis indicates that Kalliopes pole most likely points towards ecliptic coordinates = with a 10° uncertainty, Kalliopes rotation is then slightly retrograde. Kalliope has one natural satellite, Linus, or Kalliope I Linus. It is quite large, being about 28 km in diameter and it orbits about 1100 km from the center of Kalliope, equivalent to about 13.2 Kalliope radii. Linus was discovered on August 29,2001 by Jean-Luc Margot and Michael E. Brown, based on more than 5 years of regular observations of Kalliope binary system using adaptive optics systems on ground-based telescopes. The observed chords of Linus give an opportunity to estimate the size of the moonlet which was estimated to 20–28 km. Lightcurve plot of 22 Kalliope, Palmer Divide Observatory, B. D,22 Kalliope at the JPL Small-Body Database Discovery · Orbit diagram · Orbital elements · Physical parameters
2.
W. M. Keck Observatory
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The W. M. Keck Observatory is a two-telescope astronomical observatory at an elevation of 4,145 meters near the summit of Mauna Kea in the U. S. state of Hawaii. Both telescopes feature 10 m primary mirrors, currently among the largest astronomical telescopes in use, the combination of an excellent site, large optics and innovative instruments has created the two most scientifically productive telescopes on Earth. With a design in hand a search for the funding began, Keck of the W. M. Keck Foundation gave $70 million to fund the construction of the Keck I telescope. Construction of Keck I began in September 1985, with first light occurring on 24 November 1990 using only nine of the eventual 36 segments, with construction of the first telescope well advanced, further donations allowed the construction of a second telescope starting in 1991. The Keck I telescope began observations in May 1993, while first light for Keck II occurred on October 23,1996. The key advance that allowed the construction of the Keck Observatorys large telescopes was the ability to operate smaller mirror segments as a single, in the case of the Keck Observatory telescopes each of the primary mirrors is composed of 36 hexagonal segments that work together as a single unit. Each segment is 1.8 meters wide,7.5 centimeters thick, the mirrors were made from Zerodur glass-ceramic by the German company Schott AG. On the telescope, each segment is kept stable by a system of active optics, during observation, the computer-controlled system of sensors and actuators adjusts the position of each segment, relative to its neighbors, to an accuracy of four nanometers. This twice-per-second adjustment counters the effect of gravity as the telescope moves, each Keck Observatory telescope sits on an altazimuth mount. Most current 8–10 m class telescopes use altazimuth designs due to the structural requirements compared to older equatorial designs. This mounting style provides the greatest strength and stiffness for the least amount of steel, the total weight of each telescope is more than 300 tons. Two of the designs for the next generation 30 and 40 m telescopes use the same basic technology pioneered at Keck Observatory. Because of this difference in design, Keck Observatorys telescopes arguably remain the largest steerable. The telescopes are equipped with a suite of instruments, both cameras and spectrometers that allow observations across much of the visible and near infrared spectrum, construction of the telescopes was made possible through private grants totaling more than $140 million provided by the W. M. Keck Foundation. The National Aeronautics and Space Administration joined the partnership in October 1996, telescope time is allocated by the partner institutions. Caltech, the University of Hawaii System, and the University of California accept proposals from their own researchers, NASA accepts proposals from researchers based in the United States, while the National Optical Astronomy Observatory accept proposals from researchers around the world. MOSFIRE MOSFIRE is a third generation instrument for the W. M. Keck Observatory, MOSFIRE was delivered to Keck Observatory on February 8,2012 and first light on the Keck I telescope was obtained on April 4,2012. Bars move in each side to form up to 46 short slits
3.
Jean-Luc Margot
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Jean-Luc Margot is a Belgian-born astronomer and a UCLA professor who specializes in planetary sciences. Margot has discovered and studied several binary asteroids with radar and optical telescopes, in 2000, he obtained the first images of binary near-Earth asteroids and described formation of the binary by a spin-up process. Margot and his group have studied the influence of sunlight on the orbits and spins of asteroids. In 2007, Margot and collaborators determined that Mercury has a core from the analysis of small variations in the spin rate of the planet. These observations also enabled a measurement of the size of the based on a concept proposed by Stan Peale. In 2012, Margot and graduate student Julia Fang analyzed Kepler data to infer the architecture of planetary systems and they described planetary systems as flatter than pancakes. They also showed that planetary systems are dynamically packed. Margot was awarded the H. C, urey Prize by the American Astronomical Society in 2004. The asteroid 9531 Jean-Luc is named after him, Department of Earth, Planetary, and Space Sciences, UCLA Department of Physics and Astronomy, UCLA Personal web page
4.
Michael E. Brown
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Michael E. Brown is an American astronomer, who has been professor of planetary astronomy at the California Institute of Technology since 2003. His team has discovered many objects, notably the dwarf planet Eris. He is the author of How I Killed Pluto and Why It Had It Coming and he earned his A. B. in physics from Princeton University in 1987, where he was a member of the Princeton Tower Club. He did his studies at the University of California, Berkeley where he earned an M. A. degree in astronomy in 1990. Brown is well known in the community for his surveys for distant objects orbiting the Sun. His team has discovered many trans-Neptunian objects, Browns team famously named Eris and its moon Dysnomia with the informal names Xena and Gabrielle, respectively, after the two main characters of Xena, Warrior Princess. Brown originally indicated his support for Ortizs team being given credit for the discovery of Haumea, however, the Minor Planet Center only needs precise enough orbit determination on the object in order to provide discovery credit, which Ortiz provided. The then director of the IAA, José Carlos del Toro, distanced himself from Ortiz, Brown petitioned the International Astronomical Union to credit his team rather than Ortiz as the discoverers of Haumea. The IAU has deliberately not acknowledged a discoverer of Haumea, the discovery date and location are listed as March 7,2003 at Ortizs Sierra Nevada Observatory. However, the IAU accepted Browns suggested name of Haumea, which fit the names of Haumeas two moons, rather than Ortizs Ataecina. In January 2016, Brown and fellow Caltech astronomer, Konstantin Batygin, proposed the existence of Planet Nine, the two astronomers gave a recorded interview in which they described their method and reasoning for proposing Planet 9 on January 20,2016. In 2010 Brown published a memoir of his discoveries and surrounding family life, How I Killed Pluto, Brown was named one of Times 100 most influential people of 2006. In 2007 he received Caltechs annual Feynman Prize, Caltechs most prestigious teaching honor, asteroid 11714 Mikebrown, discovered on 28 April 1998, was named in his honor. In 2012, Brown was awarded the Kavli Prize in Astrophysics, Brown married Diane Binney on March 1,2003. They have one daughter, Lilah Binney Brown and he is likes being known as the Pluto Killer so uses the Twitter handle plutokiller. Konstantin Batygin Planet Nine Notes References Wilkinson, Alex
5.
Linus (mythology)
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In Greek mythology Linus refers to the musical son of Oeagrus, nominally Apollo, and the Muse Calliope. As the son of Apollo and a Muse, either Calliope or Terpsichore, he is considered the inventor of melody, Linus taught music to his brother Orpheus and then to Heracles. Linus went to Thebes and became a Theban, according to a legend, he wrote the story of Dionysus and of the other mythical legends in Pelasgic writing. His life was ended by Heracles, who killed Linus with his own lyre after he reprimanded Heracles for making errors. Linus may have been the personification of a dirge or lamentation, as there was a classical Greek song genre known as linos, a form of dirge and this would account for his being described as a son of Apollo by a Muse. Linus was also the name of a son of Apollo and Psamathe, fearing her father, she exposed the child which was found and killed by sheepdogs. For this reason, they say, Apollo sent Poine to punish the Argives, coroebus then slew Vengeance, causing a second punishment to fall upon the city that was devastated by plague
6.
Minor planet
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A minor planet is an astronomical object in direct orbit around the Sun that is neither a planet nor exclusively classified as a comet. Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, as of 2016, the orbits of 709,706 minor planets were archived at the Minor Planet Center,469,275 of which had received permanent numbers. The first minor planet to be discovered was Ceres in 1801, the term minor planet has been used since the 19th century to describe these objects. The term planetoid has also used, especially for larger objects such as those the International Astronomical Union has called dwarf planets since 2006. Historically, the asteroid, minor planet, and planetoid have been more or less synonymous. This terminology has become complicated by the discovery of numerous minor planets beyond the orbit of Jupiter. A Minor planet seen releasing gas may be classified as a comet. Before 2006, the IAU had officially used the term minor planet, during its 2006 meeting, the IAU reclassified minor planets and comets into dwarf planets and small Solar System bodies. Objects are called dwarf planets if their self-gravity is sufficient to achieve hydrostatic equilibrium, all other minor planets and comets are called small Solar System bodies. The IAU stated that the minor planet may still be used. However, for purposes of numbering and naming, the distinction between minor planet and comet is still used. Hundreds of thousands of planets have been discovered within the Solar System. The Minor Planet Center has documented over 167 million observations and 729,626 minor planets, of these,20,570 have official names. As of March 2017, the lowest-numbered unnamed minor planet is 1974 FV1, as of March 2017, the highest-numbered named minor planet is 458063 Gustavomuler. There are various broad minor-planet populations, Asteroids, traditionally, most have been bodies in the inner Solar System. Near-Earth asteroids, those whose orbits take them inside the orbit of Mars. Further subclassification of these, based on distance, is used, Apohele asteroids orbit inside of Earths perihelion distance. Aten asteroids, those that have semi-major axes of less than Earths, Apollo asteroids are those asteroids with a semimajor axis greater than Earths, while having a perihelion distance of 1.017 AU or less. Like Aten asteroids, Apollo asteroids are Earth-crossers, amor asteroids are those near-Earth asteroids that approach the orbit of Earth from beyond, but do not cross it
7.
Asteroid belt
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The asteroid belt is the circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets, the asteroid belt is also termed the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System such as near-Earth asteroids and trojan asteroids. About half the mass of the belt is contained in the four largest asteroids, Ceres, Vesta, Pallas, the total mass of the asteroid belt is approximately 4% that of the Moon, or 22% that of Pluto, and roughly twice that of Plutos moon Charon. Ceres, the belts only dwarf planet, is about 950 km in diameter, whereas Vesta, Pallas. The remaining bodies range down to the size of a dust particle, the asteroid material is so thinly distributed that numerous unmanned spacecraft have traversed it without incident. Nonetheless, collisions between large asteroids do occur, and these can form a family whose members have similar orbital characteristics. Individual asteroids within the belt are categorized by their spectra. The asteroid belt formed from the solar nebula as a group of planetesimals. Planetesimals are the precursors of the protoplanets. Between Mars and Jupiter, however, gravitational perturbations from Jupiter imbued the protoplanets with too much energy for them to accrete into a planet. Collisions became too violent, and instead of fusing together, the planetesimals, as a result,99. 9% of the asteroid belts original mass was lost in the first 100 million years of the Solar Systems history. Some fragments eventually found their way into the inner Solar System, Asteroid orbits continue to be appreciably perturbed whenever their period of revolution about the Sun forms an orbital resonance with Jupiter. At these orbital distances, a Kirkwood gap occurs as they are swept into other orbits. Classes of small Solar System bodies in other regions are the objects, the centaurs, the Kuiper belt objects, the scattered disc objects, the sednoids. On 22 January 2014, ESA scientists reported the detection, for the first definitive time, of water vapor on Ceres, the detection was made by using the far-infrared abilities of the Herschel Space Observatory. The finding was unexpected because comets, not asteroids, are considered to sprout jets. According to one of the scientists, The lines are becoming more and more blurred between comets and asteroids. This pattern, now known as the Titius–Bode law, predicted the semi-major axes of the six planets of the provided one allowed for a gap between the orbits of Mars and Jupiter
8.
Semi-major and semi-minor axes
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In geometry, the major axis of an ellipse is its longest diameter, a line segment that runs through the center and both foci, with ends at the widest points of the perimeter. The semi-major axis is one half of the axis, and thus runs from the centre, through a focus. Essentially, it is the radius of an orbit at the two most distant points. For the special case of a circle, the axis is the radius. One can think of the axis as an ellipses long radius. The semi-major axis of a hyperbola is, depending on the convention, thus it is the distance from the center to either vertex of the hyperbola. A parabola can be obtained as the limit of a sequence of ellipses where one focus is fixed as the other is allowed to move arbitrarily far away in one direction. Thus a and b tend to infinity, a faster than b, the semi-minor axis is a line segment associated with most conic sections that is at right angles with the semi-major axis and has one end at the center of the conic section. It is one of the axes of symmetry for the curve, in an ellipse, the one, in a hyperbola. The semi-major axis is the value of the maximum and minimum distances r max and r min of the ellipse from a focus — that is. In astronomy these extreme points are called apsis, the semi-minor axis of an ellipse is the geometric mean of these distances, b = r max r min. The eccentricity of an ellipse is defined as e =1 − b 2 a 2 so r min = a, r max = a. Now consider the equation in polar coordinates, with one focus at the origin, the mean value of r = ℓ / and r = ℓ /, for θ = π and θ =0 is a = ℓ1 − e 2. In an ellipse, the axis is the geometric mean of the distance from the center to either focus. The semi-minor axis of an ellipse runs from the center of the ellipse to the edge of the ellipse, the semi-minor axis is half of the minor axis. The minor axis is the longest line segment perpendicular to the axis that connects two points on the ellipses edge. The semi-minor axis b is related to the axis a through the eccentricity e. A parabola can be obtained as the limit of a sequence of ellipses where one focus is fixed as the other is allowed to move arbitrarily far away in one direction
9.
Kilometre
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The kilometre or kilometer is a unit of length in the metric system, equal to one thousand metres. K is occasionally used in some English-speaking countries as an alternative for the kilometre in colloquial writing. A slang term for the kilometre in the US military is klick, there are two common pronunciations for the word. It is generally preferred by the British Broadcasting Corporation and the Australian Broadcasting Corporation, many scientists and other users, particularly in countries where the metric system is not widely used, use the pronunciation with stress on the second syllable. The latter pronunciation follows the pattern used for the names of measuring instruments. The problem with this reasoning, however, is that the meter in those usages refers to a measuring device. The contrast is more obvious in countries using the British rather than American spelling of the word metre. When Australia introduced the system in 1975, the first pronunciation was declared official by the governments Metric Conversion Board. However, the Australian prime minister at the time, Gough Whitlam, by the 8 May 1790 decree, the Constituent assembly ordered the French Academy of Sciences to develop a new measurement system. In August 1793, the French National Convention decreed the metre as the length measurement system in the French Republic. The first name of the kilometre was Millaire, although the metre was formally defined in 1799, the myriametre was preferred to the kilometre for everyday use. The term myriamètre appeared a number of times in the text of Develeys book Physique dEmile, ou, Principes de la de la nature. French maps published in 1835 had scales showing myriametres and lieues de Poste, the Dutch, on the other hand, adopted the kilometre in 1817 but gave it the local name of the mijl. It was only in 1867 that the term became the only official unit of measure in the Netherlands to represent 1000 metres. In the US, the National Highway System Designation Act of 1995 prohibits the use of highway funds to convert existing signs or purchase new signs with metric units. Although the State DOTs had the option of using metric measurements or dual units, all of them abandoned metric measurements, the Manual on Uniform Traffic Control Devices since 2000 is published in both metric and American Customary Units. Some sporting disciplines feature 1000 m races in major events, but in other disciplines, even though records are catalogued
10.
Orbital eccentricity
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The orbital eccentricity of an astronomical object is a parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is an orbit, values between 0 and 1 form an elliptical orbit,1 is a parabolic escape orbit. The term derives its name from the parameters of conic sections and it is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the galaxy. In a two-body problem with inverse-square-law force, every orbit is a Kepler orbit, the eccentricity of this Kepler orbit is a non-negative number that defines its shape. The limit case between an ellipse and a hyperbola, when e equals 1, is parabola, radial trajectories are classified as elliptic, parabolic, or hyperbolic based on the energy of the orbit, not the eccentricity. Radial orbits have zero angular momentum and hence eccentricity equal to one, keeping the energy constant and reducing the angular momentum, elliptic, parabolic, and hyperbolic orbits each tend to the corresponding type of radial trajectory while e tends to 1. For a repulsive force only the trajectory, including the radial version, is applicable. For elliptical orbits, a simple proof shows that arcsin yields the projection angle of a circle to an ellipse of eccentricity e. For example, to view the eccentricity of the planet Mercury, next, tilt any circular object by that angle and the apparent ellipse projected to your eye will be of that same eccentricity. From Medieval Latin eccentricus, derived from Greek ἔκκεντρος ekkentros out of the center, from ἐκ- ek-, eccentric first appeared in English in 1551, with the definition a circle in which the earth, sun. Five years later, in 1556, a form of the word was added. The eccentricity of an orbit can be calculated from the state vectors as the magnitude of the eccentricity vector, e = | e | where. For elliptical orbits it can also be calculated from the periapsis and apoapsis since rp = a and ra = a, where a is the semimajor axis. E = r a − r p r a + r p =1 −2 r a r p +1 where, rp is the radius at periapsis. For Earths annual orbit path, ra/rp ratio = longest_radius / shortest_radius ≈1.034 relative to center point of path, the eccentricity of the Earths orbit is currently about 0.0167, the Earths orbit is nearly circular. Venus and Neptune have even lower eccentricity, over hundreds of thousands of years, the eccentricity of the Earths orbit varies from nearly 0.0034 to almost 0.058 as a result of gravitational attractions among the planets. The table lists the values for all planets and dwarf planets, Mercury has the greatest orbital eccentricity of any planet in the Solar System. Such eccentricity is sufficient for Mercury to receive twice as much solar irradiation at perihelion compared to aphelion, before its demotion from planet status in 2006, Pluto was considered to be the planet with the most eccentric orbit
11.
Day
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In common usage, it is either an interval equal to 24 hours or daytime, the consecutive period of time during which the Sun is above the horizon. The period of time during which the Earth completes one rotation with respect to the Sun is called a solar day, several definitions of this universal human concept are used according to context, need and convenience. In 1960, the second was redefined in terms of the motion of the Earth. The unit of measurement day, redefined in 1960 as 86400 SI seconds and symbolized d, is not an SI unit, but is accepted for use with SI. The word day may also refer to a day of the week or to a date, as in answer to the question. The life patterns of humans and many species are related to Earths solar day. In recent decades the average length of a day on Earth has been about 86400.002 seconds. A day, understood as the span of time it takes for the Earth to make one rotation with respect to the celestial background or a distant star, is called a stellar day. This period of rotation is about 4 minutes less than 24 hours, mainly due to tidal effects, the Earths rotational period is not constant, resulting in further minor variations for both solar days and stellar days. Other planets and moons have stellar and solar days of different lengths to Earths, besides the day of 24 hours, the word day is used for several different spans of time based on the rotation of the Earth around its axis. An important one is the day, defined as the time it takes for the Sun to return to its culmination point. Because the Earth orbits the Sun elliptically as the Earth spins on an inclined axis, on average over the year this day is equivalent to 24 hours. A day, in the sense of daytime that is distinguished from night-time, is defined as the period during which sunlight directly reaches the ground. The length of daytime averages slightly more than half of the 24-hour day, two effects make daytime on average longer than nights. The Sun is not a point, but has an apparent size of about 32 minutes of arc, additionally, the atmosphere refracts sunlight in such a way that some of it reaches the ground even when the Sun is below the horizon by about 34 minutes of arc. So the first light reaches the ground when the centre of the Sun is still below the horizon by about 50 minutes of arc, the difference in time depends on the angle at which the Sun rises and sets, but can amount to around seven minutes. Ancient custom has a new day start at either the rising or setting of the Sun on the local horizon, the exact moment of, and the interval between, two sunrises or sunsets depends on the geographical position, and the time of year. A more constant day can be defined by the Sun passing through the local meridian, the exact moment is dependent on the geographical longitude, and to a lesser extent on the time of the year
12.
Orbital inclination
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Orbital inclination measures the tilt of an objects orbit around a celestial body. It is expressed as the angle between a plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Earth directly above the equator, the plane of the orbit is the same as the Earths equatorial plane. The general case is that the orbit is tilted, it spends half an orbit over the northern hemisphere. If the orbit swung between 20° north latitude and 20° south latitude, then its orbital inclination would be 20°, the inclination is one of the six orbital elements describing the shape and orientation of a celestial orbit. It is the angle between the plane and the plane of reference, normally stated in degrees. For a satellite orbiting a planet, the plane of reference is usually the plane containing the planets equator, for planets in the Solar System, the plane of reference is usually the ecliptic, the plane in which the Earth orbits the Sun. This reference plane is most practical for Earth-based observers, therefore, Earths inclination is, by definition, zero. Inclination could instead be measured with respect to another plane, such as the Suns equator or the invariable plane, the inclination of orbits of natural or artificial satellites is measured relative to the equatorial plane of the body they orbit, if they orbit sufficiently closely. The equatorial plane is the perpendicular to the axis of rotation of the central body. An inclination of 30° could also be described using an angle of 150°, the convention is that the normal orbit is prograde, an orbit in the same direction as the planet rotates. Inclinations greater than 90° describe retrograde orbits, thus, An inclination of 0° means the orbiting body has a prograde orbit in the planets equatorial plane. An inclination greater than 0° and less than 90° also describe prograde orbits, an inclination of 63. 4° is often called a critical inclination, when describing artificial satellites orbiting the Earth, because they have zero apogee drift. An inclination of exactly 90° is an orbit, in which the spacecraft passes over the north and south poles of the planet. An inclination greater than 90° and less than 180° is a retrograde orbit, an inclination of exactly 180° is a retrograde equatorial orbit. For gas giants, the orbits of moons tend to be aligned with the giant planets equator, the inclination of exoplanets or members of multiple stars is the angle of the plane of the orbit relative to the plane perpendicular to the line-of-sight from Earth to the object. An inclination of 0° is an orbit, meaning the plane of its orbit is parallel to the sky. An inclination of 90° is an orbit, meaning the plane of its orbit is perpendicular to the sky
13.
Natural satellite
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A natural satellite or moon is, in the most common usage, an astronomical body that orbits a planet or minor planet. In the Solar System there are six planetary satellite systems containing 178 known natural satellites, four IAU-listed dwarf planets are also known to have natural satellites, Pluto, Haumea, Makemake, and Eris. As of January 2012, over 200 minor-planet moons have been discovered, the Earth–Moon system is unique in that the ratio of the mass of the Moon to the mass of Earth is much greater than that of any other natural-satellite–planet ratio in the Solar System. At 3,474 km across, Earths Moon is 0.27 times the diameter of Earth, the first known natural satellite was the Moon, but it was considered a planet until Copernicus introduction of heliocentrism in 1543. Until the discovery of the Galilean satellites in 1610, however, galileo chose to refer to his discoveries as Planetæ, but later discoverers chose other terms to distinguish them from the objects they orbited. The first to use of the satellite to describe orbiting bodies was the German astronomer Johannes Kepler in his pamphlet Narratio de Observatis a se quatuor Iouis satellitibus erronibus in 1610. He derived the term from the Latin word satelles, meaning guard, attendant, or companion, the term satellite thus became the normal one for referring to an object orbiting a planet, as it avoided the ambiguity of moon. In 1957, however, the launching of the artificial object Sputnik created a need for new terminology, to further avoid ambiguity, the convention is to capitalize the word Moon when referring to Earths natural satellite, but not when referring to other natural satellites. A few recent authors define moon as a satellite of a planet or minor planet, there is no established lower limit on what is considered a moon. Small asteroid moons, such as Dactyl, have also been called moonlets, the upper limit is also vague. Two orbiting bodies are described as a double body rather than primary. Asteroids such as 90 Antiope are considered double asteroids, but they have not forced a clear definition of what constitutes a moon, some authors consider the Pluto–Charon system to be a double planet. In contrast, irregular satellites are thought to be captured asteroids possibly further fragmented by collisions, most of the major natural satellites of the Solar System have regular orbits, while most of the small natural satellites have irregular orbits. The Moon and possibly Charon are exceptions among large bodies in that they are thought to have originated by the collision of two large proto-planetary objects. The material that would have placed in orbit around the central body is predicted to have reaccreted to form one or more orbiting natural satellites. As opposed to planetary-sized bodies, asteroid moons are thought to form by this process. Triton is another exception, although large and in a close, circular orbit, its motion is retrograde, most regular moons in the Solar System are tidally locked to their respective primaries, meaning that the same side of the natural satellite always faces its planet. The only known exception is Saturns natural satellite Hyperion, which rotates chaotically because of the influence of Titan
14.
Mass
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In physics, mass is a property of a physical body. It is the measure of a resistance to acceleration when a net force is applied. It also determines the strength of its gravitational attraction to other bodies. The basic SI unit of mass is the kilogram, Mass is not the same as weight, even though mass is often determined by measuring the objects weight using a spring scale, rather than comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity and this is because weight is a force, while mass is the property that determines the strength of this force. In Newtonian physics, mass can be generalized as the amount of matter in an object, however, at very high speeds, special relativity postulates that energy is an additional source of mass. Thus, any body having mass has an equivalent amount of energy. In addition, matter is a defined term in science. There are several distinct phenomena which can be used to measure mass, active gravitational mass measures the gravitational force exerted by an object. Passive gravitational mass measures the force exerted on an object in a known gravitational field. The mass of an object determines its acceleration in the presence of an applied force, according to Newtons second law of motion, if a body of fixed mass m is subjected to a single force F, its acceleration a is given by F/m. A bodys mass also determines the degree to which it generates or is affected by a gravitational field and this is sometimes referred to as gravitational mass. The standard International System of Units unit of mass is the kilogram, the kilogram is 1000 grams, first defined in 1795 as one cubic decimeter of water at the melting point of ice. Then in 1889, the kilogram was redefined as the mass of the prototype kilogram. As of January 2013, there are proposals for redefining the kilogram yet again. In this context, the mass has units of eV/c2, the electronvolt and its multiples, such as the MeV, are commonly used in particle physics. The atomic mass unit is 1/12 of the mass of a carbon-12 atom, the atomic mass unit is convenient for expressing the masses of atoms and molecules. Outside the SI system, other units of mass include, the slug is an Imperial unit of mass, the pound is a unit of both mass and force, used mainly in the United States
15.
Density
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The density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ, although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume, ρ = m V, where ρ is the density, m is the mass, and V is the volume. In some cases, density is defined as its weight per unit volume. For a pure substance the density has the numerical value as its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity, osmium and iridium are the densest known elements at standard conditions for temperature and pressure but certain chemical compounds may be denser. Thus a relative density less than one means that the floats in water. The density of a material varies with temperature and pressure and this variation is typically small for solids and liquids but much greater for gases. Increasing the pressure on an object decreases the volume of the object, increasing the temperature of a substance decreases its density by increasing its volume. In most materials, heating the bottom of a results in convection of the heat from the bottom to the top. This causes it to rise relative to more dense unheated material, the reciprocal of the density of a substance is occasionally called its specific volume, a term sometimes used in thermodynamics. Density is a property in that increasing the amount of a substance does not increase its density. Archimedes knew that the irregularly shaped wreath could be crushed into a cube whose volume could be calculated easily and compared with the mass, upon this discovery, he leapt from his bath and ran naked through the streets shouting, Eureka. As a result, the term eureka entered common parlance and is used today to indicate a moment of enlightenment, the story first appeared in written form in Vitruvius books of architecture, two centuries after it supposedly took place. Some scholars have doubted the accuracy of this tale, saying among other things that the method would have required precise measurements that would have been difficult to make at the time, from the equation for density, mass density has units of mass divided by volume. As there are units of mass and volume covering many different magnitudes there are a large number of units for mass density in use. The SI unit of kilogram per metre and the cgs unit of gram per cubic centimetre are probably the most commonly used units for density.1,000 kg/m3 equals 1 g/cm3. In industry, other larger or smaller units of mass and or volume are often more practical, see below for a list of some of the most common units of density
16.
Escape velocity
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The escape velocity from Earth is about 11.186 km/s at the surface. More generally, escape velocity is the speed at which the sum of a kinetic energy. With escape velocity in a direction pointing away from the ground of a massive body, once escape velocity is achieved, no further impulse need be applied for it to continue in its escape. When given a speed V greater than the speed v e. In these equations atmospheric friction is not taken into account, escape velocity is only required to send a ballistic object on a trajectory that will allow the object to escape the gravity well of the mass M. The existence of escape velocity is a consequence of conservation of energy, by adding speed to the object it expands the possible places that can be reached until with enough energy they become infinite. For a given gravitational potential energy at a position, the escape velocity is the minimum speed an object without propulsion needs to be able to escape from the gravity. Escape velocity is actually a speed because it does not specify a direction, no matter what the direction of travel is, the simplest way of deriving the formula for escape velocity is to use conservation of energy. Imagine that a spaceship of mass m is at a distance r from the center of mass of the planet and its initial speed is equal to its escape velocity, v e. At its final state, it will be a distance away from the planet. The same result is obtained by a calculation, in which case the variable r represents the radial coordinate or reduced circumference of the Schwarzschild metric. All speeds and velocities measured with respect to the field, additionally, the escape velocity at a point in space is equal to the speed that an object would have if it started at rest from an infinite distance and was pulled by gravity to that point. In common usage, the point is on the surface of a planet or moon. On the surface of the Earth, the velocity is about 11.2 km/s. However, at 9,000 km altitude in space, it is less than 7.1 km/s. The escape velocity is independent of the mass of the escaping object and it does not matter if the mass is 1 kg or 1,000 kg, what differs is the amount of energy required. For an object of mass m the energy required to escape the Earths gravitational field is GMm / r, a related quantity is the specific orbital energy which is essentially the sum of the kinetic and potential energy divided by the mass. An object has reached escape velocity when the orbital energy is greater or equal to zero
17.
Tidal locking
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Tidal locking occurs when, over the course of an orbit, there is no net transfer of angular momentum between an astronomical body and its gravitational partner. This state can result from the gradient between two co-orbiting bodies, acting over a sufficiently long period of time. In the case where the orbital eccentricity is zero, tidal locking results in one hemisphere of the revolving object constantly facing its partner. For example, the side of the Moon always faces the Earth. A tidally locked body in synchronous rotation takes just as long to rotate around its own axis as it does to revolve around its partner, usually, only the satellite is tidally locked to the larger body. However, if both the difference between the two bodies and the distance between them are relatively small, each may be tidally locked to the other, this is the case for Pluto. This effect is employed to stabilize some artificial satellites, the possibility of lifeforms existing on tidally-locked planets has been debated. The change in rotation rate necessary to lock a body B to a larger body A is caused by the torque applied by As gravity on bulges it has induced on B by tidal forces. These distortions are known as tidal bulges, when B is not yet tidally locked, the bulges travel over its surface, with one of the two high tidal bulges traveling close to the point where body A is overhead. Smaller bodies also experience distortion, but this distortion is less regular, the material of B exerts resistance to this periodic reshaping caused by the tidal force. In effect, some time is required to reshape B to the equilibrium shape. Seen from a point in space, the points of maximum bulge extension are displaced from the axis oriented toward A. Because the bulges are now displaced from the A–B axis, As gravitational pull on the mass in them exerts a torque on B. The torque on the A-facing bulge acts to bring Bs rotation in line with its period, whereas the back bulge. However, the bulge on the A-facing side is closer to A than the bulge by a distance of approximately Bs diameter. The net resulting torque from both bulges, then, is always in the direction that acts to synchronize Bs rotation with its orbital period and this results in a raising of Bs orbit about A in tandem with its rotational slowdown. For the other case where B starts off rotating too slowly, the tidal locking effect is also experienced by the larger body A, but at a slower rate because Bs gravitational effect is weaker due to Bs smaller mass. For example, Earths rotation is gradually being slowed by the Moon, current estimations are that this has helped lengthen the Earth day from about 6 hours to the current 24 hours
18.
Axial tilt
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In astronomy, axial tilt, also known as obliquity, is the angle between an objects rotational axis and its orbital axis, or, equivalently, the angle between its equatorial plane and orbital plane. At an obliquity of zero, the two axes point in the direction, i. e. the rotational axis is perpendicular to the orbital plane. Over the course of an orbit, the obliquity usually does not change considerably, and this causes one pole to be directed more toward the Sun on one side of the orbit, and the other pole on the other side — the cause of the seasons on the Earth. Earths obliquity oscillates between 22.1 and 24.5 degrees on a 41, 000-year cycle, the mean obliquity is currently 23°26′13. 4″. There are two methods of specifying tilt. The IAU also uses the rule to define a positive pole for the purpose of determining orientation. Using this convention, Venus is tilted 177° and it is denoted by the Greek letter ε. Earth currently has a tilt of about 23. 4°. This value remains about the relative to a stationary orbital plane throughout the cycles of axial precession. But the ecliptic due to planetary perturbations, and the obliquity of the ecliptic is not a fixed quantity. At present, it is decreasing at a rate of about 47″ per century, Earths obliquity may have been reasonably accurately measured as early as 1100 BC in India and China. The ancient Greeks had good measurements of the obliquity since about 350 BC, about 830 AD, the Caliph Al-Mamun of Baghdad directed his astronomers to measure the obliquity, and the result was used in the Arab world for many years. It was widely believed, during the Middle Ages, that both precession and Earths obliquity oscillated around a value, with a period of 672 years. Earths axis remains tilted in the direction with reference to the background stars throughout a year. This means that one pole will be directed away from the Sun at one side of the orbit and this is the cause of Earths seasons. Summer occurs in the Northern hemisphere when the pole is directed toward the Sun. Variations in Earths axial tilt can influence the seasons and is likely a factor in climate change. The exact angular value of the obliquity is found by observation of the motions of Earth, from 1984, the Jet Propulsion Laboratorys DE series of computer-generated ephemerides took over as the fundamental ephemeris of the Astronomical Almanac
19.
Temperature
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A temperature is an objective comparative measurement of hot or cold. It is measured by a thermometer, several scales and units exist for measuring temperature, the most common being Celsius, Fahrenheit, and, especially in science, Kelvin. Absolute zero is denoted as 0 K on the Kelvin scale, −273.15 °C on the Celsius scale, the kinetic theory offers a valuable but limited account of the behavior of the materials of macroscopic bodies, especially of fluids. Temperature is important in all fields of science including physics, geology, chemistry, atmospheric sciences, medicine. The Celsius scale is used for temperature measurements in most of the world. Because of the 100 degree interval, it is called a centigrade scale.15, the United States commonly uses the Fahrenheit scale, on which water freezes at 32°F and boils at 212°F at sea-level atmospheric pressure. Many scientific measurements use the Kelvin temperature scale, named in honor of the Scottish physicist who first defined it and it is a thermodynamic or absolute temperature scale. Its zero point, 0K, is defined to coincide with the coldest physically-possible temperature and its degrees are defined through thermodynamics. The temperature of zero occurs at 0K = −273. 15°C. For historical reasons, the triple point temperature of water is fixed at 273.16 units of the measurement increment, Temperature is one of the principal quantities in the study of thermodynamics. There is a variety of kinds of temperature scale and it may be convenient to classify them as empirically and theoretically based. Empirical temperature scales are historically older, while theoretically based scales arose in the middle of the nineteenth century, empirically based temperature scales rely directly on measurements of simple physical properties of materials. For example, the length of a column of mercury, confined in a capillary tube, is dependent largely on temperature. Such scales are only within convenient ranges of temperature. For example, above the point of mercury, a mercury-in-glass thermometer is impracticable. A material is of no use as a thermometer near one of its phase-change temperatures, in spite of these restrictions, most generally used practical thermometers are of the empirically based kind. Especially, it was used for calorimetry, which contributed greatly to the discovery of thermodynamics, nevertheless, empirical thermometry has serious drawbacks when judged as a basis for theoretical physics. Theoretically based temperature scales are based directly on theoretical arguments, especially those of thermodynamics, kinetic theory and they rely on theoretical properties of idealized devices and materials
20.
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
21.
Celsius
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Celsius, also known as centigrade, is a metric scale and unit of measurement for temperature. As an SI derived unit, it is used by most countries in the world and it is named after the Swedish astronomer Anders Celsius, who developed a similar temperature scale. The degree Celsius can refer to a temperature on the Celsius scale as well as a unit to indicate a temperature interval. Before being renamed to honour Anders Celsius in 1948, the unit was called centigrade, from the Latin centum, which means 100, and gradus, which means steps. The scale is based on 0° for the point of water. This scale is widely taught in schools today, by international agreement the unit degree Celsius and the Celsius scale are currently defined by two different temperatures, absolute zero, and the triple point of VSMOW. This definition also precisely relates the Celsius scale to the Kelvin scale, absolute zero, the lowest temperature possible, is defined as being precisely 0 K and −273.15 °C. The temperature of the point of water is defined as precisely 273.16 K at 611.657 pascals pressure. This definition fixes the magnitude of both the degree Celsius and the kelvin as precisely 1 part in 273.16 of the difference between absolute zero and the point of water. Thus, it sets the magnitude of one degree Celsius and that of one kelvin as exactly the same, additionally, it establishes the difference between the two scales null points as being precisely 273.15 degrees. In his paper Observations of two persistent degrees on a thermometer, he recounted his experiments showing that the point of ice is essentially unaffected by pressure. He also determined with precision how the boiling point of water varied as a function of atmospheric pressure. He proposed that the point of his temperature scale, being the boiling point. This pressure is known as one standard atmosphere, the BIPMs 10th General Conference on Weights and Measures later defined one standard atmosphere to equal precisely 1013250dynes per square centimetre. On 19 May 1743 he published the design of a mercury thermometer, in 1744, coincident with the death of Anders Celsius, the Swedish botanist Carolus Linnaeus reversed Celsiuss scale. In it, Linnaeus recounted the temperatures inside the orangery at the University of Uppsala Botanical Garden, since the 19th century, the scientific and thermometry communities worldwide referred to this scale as the centigrade scale. Temperatures on the scale were often reported simply as degrees or. More properly, what was defined as centigrade then would now be hectograde.2 gradians, for scientific use, Celsius is the term usually used, with centigrade otherwise continuing to be in common but decreasing use, especially in informal contexts in English-speaking countries
22.
Minor-planet moon
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A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. It is thought that many asteroids and Kuiper belt objects may possess moons, the first modern era mention of the possibility of an asteroid satellite was in connection with an occultation of the bright star Gamma Ceti by the minor planet Hebe in 1977. The observer, amateur astronomer Paul D. Maley, detected an unmistakable 0.5 second disappearance of this naked eye star from a site near Victoria, many hours later, several observations were reported in Mexico attributed to the occultation by Hebe itself. Although not confirmed this documents the first formally documented case of a companion of an asteroid. As of October 2016, there are over 300 minor planets known to have moons, in addition to the terms satellite and moon, the term binary is sometimes used for minor planets with moons, and triple for minor planets with two moons. If one object is much bigger it can be referred to as the primary, when binary minor planets are similar in size, the Minor Planet Center refers to them as binary companions instead of referring to the smaller body as a satellite. A good example of a true binary is the 90 Antiope system, small satellites are often referred to as moonlets. As of February 2017, over 330 moons of planets have been discovered. For example, in 1978, stellar occultation observations were claimed as evidence of a satellite for the asteroid 532 Herculina, however, later more-detailed imaging by the Hubble Telescope did not reveal a satellite, and the current consensus is that Herculina does not have a significant satellite. There were other reports of asteroids having companions in the following years. In 1993, the first asteroid moon was confirmed when the Galileo probe discovered the small Dactyl orbiting 243 Ida in the asteroid belt, the second was discovered around 45 Eugenia in 1998. In 2001,617 Patroclus and its same-sized companion Menoetius became the first known asteroids in the Jupiter trojans. The first trans-Neptunian binary after Pluto–Charon,1998 WW31, was resolved in 2002. Triple asteroids, or trinary asteroids, are known since 2005 and this was followed by the discovery of a second moon orbiting 45 Eugenia. Also in 2005, the Kuiper belt object Haumea was discovered to have two moons, making it the second KBO after Pluto known to have more than one moon, additionally,216 Kleopatra and 93 Minerva were discovered to be trinary asteroids in 2008 and 2009 respectively. Since the first few trinary asteroids were discovered, more continue to be discovered at a rate of one a year. Most recently discovered was a moon orbiting the belt asteroid 130 Elektra. List of multiple planets, The data about the populations of binary objects are still patchy
23.
Astronomer
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An astronomer is a scientist in the field of astronomy who concentrates their studies on a specific question or field outside of the scope of Earth. They look at stars, planets, moons, comets and galaxies, as well as other celestial objects — either in observational astronomy. Examples of topics or fields astronomers work on include, planetary science, solar astronomy, there are also related but distinct subjects like physical cosmology which studies the Universe as a whole. Astronomers usually fit into two types, Observational astronomers make direct observations of planets, stars and galaxies, and analyze the data, theoretical astronomers create and investigate models of things that cannot be observed. They use this data to create models or simulations to theorize how different celestial bodies work, there are further subcategories inside these two main branches of astronomy such as planetary astronomy, galactic astronomy or physical cosmology. Today, that distinction has disappeared and the terms astronomer. Professional astronomers are highly educated individuals who typically have a Ph. D. in physics or astronomy and are employed by research institutions or universities. They spend the majority of their time working on research, although quite often have other duties such as teaching, building instruments. The number of astronomers in the United States is actually quite small. The American Astronomical Society, which is the organization of professional astronomers in North America, has approximately 7,000 members. This number includes scientists from other such as physics, geology. The International Astronomical Union comprises almost 10,145 members from 70 different countries who are involved in research at the Ph. D. level. Before CCDs, photographic plates were a method of observation. Modern astronomers spend relatively little time at telescopes usually just a few weeks per year, analysis of observed phenomena, along with making predictions as to the causes of what they observe, takes the majority of observational astronomers time. Astronomers who serve as faculty spend much of their time teaching undergraduate and graduate classes, most universities also have outreach programs including public telescope time and sometimes planetariums as a public service to encourage interest in the field. Those who become astronomers usually have a background in maths, sciences. Taking courses that teach how to research, write and present papers are also invaluable, in college/university most astronomers get a Ph. D. in astronomy or physics. Keeping in mind how few there are it is understood that graduate schools in this field are very competitive
24.
Hawaii
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Hawaii is the 50th and most recent state to have joined the United States of America, having received statehood on August 21,1959. Hawaii is the only U. S. state located in Oceania and it is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean. Hawaii is the only U. S. state not located in the Americas, the state encompasses nearly the entire volcanic Hawaiian archipelago, which comprises hundreds of islands spread over 1,500 miles. At the southeastern end of the archipelago, the eight main islands are—in order from northwest to southeast, Niʻihau, Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Kahoʻolawe, Maui, and the Island of Hawaiʻi. The last is the largest island in the group, it is called the Big Island or Hawaiʻi Island to avoid confusion with the state or archipelago. The archipelago is physiographically and ethnologically part of the Polynesian subregion of Oceania, Hawaii has over a million permanent residents, along with many visitors and U. S. military personnel. Its capital is Honolulu on the island of Oʻahu, Hawaii is the 8th-smallest and the 11th-least populous, but the 13th-most densely populated of the fifty U. S. states. It is the state with an Asian plurality. The states coastline is about 750 miles long, the fourth longest in the U. S. after the coastlines of Alaska, Florida, the state of Hawaii derives its name from the name of its largest island, Hawaiʻi. A common Hawaiian explanation of the name of Hawaiʻi is that was named for Hawaiʻiloa and he is said to have discovered the islands when they were first settled. The Hawaiian language word Hawaiʻi is very similar to Proto-Polynesian *Sawaiki, cognates of Hawaiʻi are found in other Polynesian languages, including Māori, Rarotongan and Samoan. According to linguists Pukui and Elbert, lsewhere in Polynesia, Hawaiʻi or a cognate is the name of the underworld or of the home, but in Hawaii. A somewhat divisive political issue arose in 1978 when the Constitution of the State of Hawaii added Hawaiian as an official state language. The title of the constitution is The Constitution of the State of Hawaii. Article XV, Section 1 of the Constitution uses The State of Hawaii, diacritics were not used because the document, drafted in 1949, predates the use of the okina and the kahakō in modern Hawaiian orthography. The exact spelling of the name in the Hawaiian language is Hawaiʻi. In the Hawaii Admission Act that granted Hawaiian statehood, the government recognized Hawaii as the official state name. Official government publications, department and office titles, and the Seal of Hawaii use the spelling with no symbols for glottal stops or vowel length
25.
Mauna Kea
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Mauna Kea, is a dormant volcano on the island of Hawaii. Standing 4,207 m above sea level, its peak is the highest point in the state of Hawaii, much of the mountain is under water, when measured from its oceanic base, Mauna Kea is over 10,000 m tall. Mauna Kea is about a years old, and has thus passed the most active shield stage of life hundreds of thousands of years ago. In its current post-shield state, its lava is more viscous, Mauna Kea last erupted 6,000 to 4,000 years ago and is now considered dormant. In Hawaiian mythology, the peaks of the island of Hawaiʻi are sacred, an ancient law allowed only high-ranking aliʻi to visit its peak. Ancient Hawaiians living on the slopes of Mauna Kea relied on its extensive forests for food, when Europeans arrived in the late 18th century, settlers introduced cattle, sheep and game animals, many of which became feral and began to damage the mountains ecological balance. With its high elevation, dry environment, and stable airflow, since the creation of an access road in 1964, thirteen telescopes funded by eleven countries have been constructed at the summit. The Mauna Kea Observatories are used for research across the electromagnetic spectrum from visible light to radio. Their construction on a landscape considered sacred by Native Hawaiians continues to be a topic of debate, Mauna Kea is one of five hotspot volcanoes that form the island of Hawaii, the largest and youngest island of the Hawaiian–Emperor seamount chain. Of these five volcanoes, Mauna Kea is the fourth oldest and it began as a preshield volcano driven by the Hawaii hotspot around one million years ago, and became exceptionally active during its shield stage until 500,000 years ago. Mauna Kea entered its quieter post-shield stage 250,000 to 200,000 years ago, Mauna Kea does not have a visible summit caldera, but contains a number of small cinder and pumice cones near its summit. A former summit caldera may have been filled and buried by later summit eruption deposits, Mauna Kea is over 3,200 km3 in volume, so massive that it and its neighbor, Mauna Loa, depress the ocean crust beneath it by 6 km. The volcano continues to slip and flatten under its own weight at a rate of less than 0.2 mm per year, much of its mass lies east of its present summit. Mauna Kea stands 4,205 m above sea level, just 35 m higher than its neighbor Mauna Loa, measured from its base on the ocean floor, it rises over 10,000 m, significantly greater than the elevation of Mount Everest above sea level. Like all Hawaiian volcanoes, Mauna Kea has been created as the Pacific tectonic plate has moved over the Hawaiian hotspot in the Earths underlying mantle. The Hawaii island volcanoes are the most recent evidence of this process that, the prevailing, though not completely settled, view is that the hotspot has been largely stationary within the planets mantle for much, if not all of the Cenozoic Era. However, while Hawaiian volcanism is well-understood and extensively studied, there remains no definite explanation of the mechanism causes the hotspot effect. Lava flows from Mauna Kea overlapped in complex layers with those of its neighbors during its growth, most prominently, Mauna Kea is built upon older flows from Kohala to the northwest, and intersects the base of Mauna Loa to the south
26.
International Astronomical Union
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The International Astronomical Union is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy. Among other activities, it acts as the recognized authority for assigning designations to celestial bodies. The IAU is a member of the International Council for Science and its main objective is to promote and safeguard the science of astronomy in all its aspects through international cooperation. The IAU maintains friendly relations with organizations that include amateur astronomers in their membership, the IAU has its head office on the second floor of the Institut dAstrophysique de Paris in the 14th arrondissement of Paris. The IAU is also responsible for the system of astronomical telegrams which are produced and distributed on its behalf by the Central Bureau for Astronomical Telegrams, the Minor Planet Center also operates under the IAU, and is a clearinghouse for all non-planetary or non-moon bodies in the Solar System. The Working Group for Meteor Shower Nomenclature and the Meteor Data Center coordinate the nomenclature of meteor showers, the IAU was founded on July 28,1919, at the Constitutive Assembly of the International Research Council held in Brussels, Belgium. The 7 initial member states were Belgium, Canada, France, Great Britain, Greece, Japan, the first executive committee consisted of Benjamin Baillaud, Alfred Fowler, and four vice presidents, William Campbell, Frank Dyson, Georges Lecointe, and Annibale Riccò. Thirty-two Commissions were appointed at the Brussels meeting and focused on topics ranging from relativity to minor planets, the reports of these 32 Commissions formed the main substance of the first General Assembly, which took place in Rome, Italy, May 2–10,1922. By the end of the first General Assembly, ten nations had joined the Union. Although the Union was officially formed eight months after the end of World War I, the first 50 years of the Unions history are well documented. Subsequent history is recorded in the form of reminiscences of past IAU Presidents, twelve of the fourteen past General Secretaries in the period 1964-2006 contributed their recollections of the Unions history in IAU Information Bulletin No.100. Six past IAU Presidents in the period 1976–2003 also contributed their recollections in IAU Information Bulletin No.104, the IAU includes a total of 12,664 individual members who are professional astronomers from 96 countries worldwide. 83% of all members are male, while 17% are female, among them the unions current president. Membership also includes 79 national members, professional astronomical communities representing their countrys affiliation with the IAU, the sovereign body of the IAU is its General Assembly, which comprises all members. The Assembly determines IAU policy, approves the Statutes and By-Laws of the Union, the right to vote on matters brought before the Assembly varies according to the type of business under discussion. On budget matters, votes are weighted according to the subscription levels of the national members. A second category vote requires a turnout of at least two-thirds of national members in order to be valid, an absolute majority is sufficient for approval in any vote, except for Statute revision which requires a two-thirds majority. An equality of votes is resolved by the vote of the President of the Union, since 1922, the IAU General Assembly meets every three years, with the exception of the period between 1938 and 1948, due to World War II
27.
Calliope
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In Greek mythology, Calliope is the muse who presides over eloquence and epic poetry, so called from the ecstatic harmony of her voice. She is spoken of by Hesiod and Ovid as the Chief of all Muses and she is mostly stated to be the eldest of the Muses, sometimes vying with her sister Urania for the position. Calliope also had two sons, Orpheus and Linus, by either Apollo or the king Oeagrus of Thrace. She taught Orpheus verses for singing, according to Hesiod, she was also the wisest of the Muses, as well as the most assertive. Calliope married Oeagrus close to Pimpleia, Olympus and she is said to have defeated the daughters of Pierus, king of Thessaly, in a singing match, and then, to punish their presumption, turned them into magpies. She was sometimes believed to be Homers muse for the Iliad, the Roman epic poet, Virgil, invokes her in the Aeneid. Calliope is usually seen with a tablet in her hand. At times, she is depicted carrying a roll of paper or a book or wearing a gold crown and she would also be seen with her children. The Italian poet, Dante Alighieri, in his Divine Comedy, makes reference to Calliope, Media related to Calliope at Wikimedia Commons Theoi. com – Calliope Warburg Institute Iconographic Database
28.
Linus Torvalds
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He also created the distributed revision control system Git and the diving logging and planning software Subsurface. He is also the recipient of the 2014 IEEE Computer Society Computer Pioneer Award, Torvalds was born in Helsinki, Finland in 1969. He is the son of journalists Anna and Nils Torvalds, both of his parents were campus radicals at the University of Helsinki in the 1960s. His family belongs to the Swedish-speaking minority, Torvalds attended the University of Helsinki between 1988 and 1996, graduating with a masters degree in computer science from NODES research group. In the army he held the rank of Second Lieutenant, with the role of a ballistic calculation officer, Torvalds bought computer science professor Andrew Tanenbaums book Operating Systems, Design and Implementation, in which Tanenbaum describes MINIX, an educational stripped-down version of Unix. In 1990, he resumed his university studies, and was exposed to UNIX for the first time, thesis was titled Linux, A Portable Operating System. His interest in computers began with a Commodore VIC-20, at the age of 11 in 1981, initially programming in BASIC and he did not make use of assembly language. After the VIC-20 he purchased a Sinclair QL, which he modified extensively, especially its operating system, because it was so hard to get software for it in Finland, Linus wrote his own assembler and editor for the QL, as well as a few games. He is known to have written a Pac-Man clone named Cool Man, on January 5,1991 he purchased an Intel 80386-based clone of IBM PC before receiving his MINIX copy, which in turn enabled him to begin work on Linux. The first prototypes of Linux were publicly released later that year, version 1.0 was released on March 14,1994. Torvalds used Stallmans GNU General Public License version 2 for his Linux kernel, after a visit to Transmeta in late 1996, Torvalds accepted a position at the company in California, where he would work from February 1997 until June 2003. He then moved to the Open Source Development Labs, which has merged with the Free Standards Group to become the Linux Foundation. In June 2004, Torvalds and his moved to Dunthorpe, Oregon, to be closer to the OSDLs Beaverton. From 1997 to 1999, he was involved in 86open helping to choose the standard format for Linux. In 1999, he was named by the MIT Technology Review TR100 as one of the worlds top 100 innovators under age 35, in 1999, Red Hat and VA Linux, both leading developers of Linux-based software, presented Torvalds with stock options in gratitude for his creation. That same year both companies went public and Torvaldss share value temporarily shot up to roughly US$20 million and his personal mascot is a penguin nicknamed Tux, which has been widely adopted by the Linux community as the mascot of the Linux kernel. Although Torvalds believes open source is the right way to do software, he also has said that he uses the best tool for the job. He was criticized for his use and alleged advocacy of the proprietary BitKeeper software for control in the Linux kernel
29.
Linux
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Linux is a Unix-like computer operating system assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on September 17,1991 by Linus Torvalds, the Free Software Foundation uses the name GNU/Linux to describe the operating system, which has led to some controversy. Linux was originally developed for computers based on the Intel x86 architecture. Because of the dominance of Android on smartphones, Linux has the largest installed base of all operating systems. Linux is also the operating system on servers and other big iron systems such as mainframe computers. It is used by around 2. 3% of desktop computers, the Chromebook, which runs on Chrome OS, dominates the US K–12 education market and represents nearly 20% of the sub-$300 notebook sales in the US. Linux also runs on embedded systems – devices whose operating system is built into the firmware and is highly tailored to the system. This includes TiVo and similar DVR devices, network routers, facility automation controls, televisions, many smartphones and tablet computers run Android and other Linux derivatives. The development of Linux is one of the most prominent examples of free, the underlying source code may be used, modified and distributed—commercially or non-commercially—by anyone under the terms of its respective licenses, such as the GNU General Public License. Typically, Linux is packaged in a known as a Linux distribution for both desktop and server use. Distributions intended to run on servers may omit all graphical environments from the standard install, because Linux is freely redistributable, anyone may create a distribution for any intended use. The Unix operating system was conceived and implemented in 1969 at AT&Ts Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, first released in 1971, Unix was written entirely in assembly language, as was common practice at the time. Later, in a key pioneering approach in 1973, it was rewritten in the C programming language by Dennis Ritchie, the availability of a high-level language implementation of Unix made its porting to different computer platforms easier. Due to an earlier antitrust case forbidding it from entering the computer business, as a result, Unix grew quickly and became widely adopted by academic institutions and businesses. In 1984, AT&T divested itself of Bell Labs, freed of the legal obligation requiring free licensing, the GNU Project, started in 1983 by Richard Stallman, has the goal of creating a complete Unix-compatible software system composed entirely of free software. Later, in 1985, Stallman started the Free Software Foundation, by the early 1990s, many of the programs required in an operating system were completed, although low-level elements such as device drivers, daemons, and the kernel were stalled and incomplete. Linus Torvalds has stated that if the GNU kernel had been available at the time, although not released until 1992 due to legal complications, development of 386BSD, from which NetBSD, OpenBSD and FreeBSD descended, predated that of Linux. Torvalds has also stated that if 386BSD had been available at the time, although the complete source code of MINIX was freely available, the licensing terms prevented it from being free software until the licensing changed in April 2000
30.
Linus van Pelt
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Linus van Pelt is a character in Charles M. Schulzs comic strip Peanuts. The best friend of Charlie Brown, Linus is also the brother of Lucy van Pelt. He first appeared on September 19,1952, but was not mentioned by name until three days later and he was first referred to two months earlier, on July 14. Linus spoke his first words in 1954, the year he was shown with his security blanket. He invented his own legendary being, the Great Pumpkin, who, Linus claims, appears every Halloween at the most sincere pumpkin patch, bearing gifts. On one occasion, Linus had a lead in the polls for school president—until he brought up the subject of the Great Pumpkin. A similar occurrence was featured in a strip with the storyline, Charlie Brown asks him why he had to bring up the Great Pumpkin. After Linus says that Charlie Brown is looking at him as if he was crazy, Charlie Brown responds, Linus is almost never seen without his blue security blanket, which debuted in the June 1,1954, strip. He holds it over his shoulder while sucking his thumb, ridicule of the habit is not a major concern for him. The blanket, it out, is an autonomous entity. In the special A Boy Named Charlie Brown, it performed a dance routine with Linus upon being reunited with its owner. Linus had lost the blanket, causing him depression, panic attacks, sweating, in the earlier strips, Linuss relationship to his blanket was one of intense emotional attachment to the point of manifesting physical symptoms if he was deprived of it even for a short while. He suffered weakness and dizziness, for example, when Lucy took it from him long enough to have it laundered. In A Boy Named Charlie Brown, Linus manifested similar symptoms when he gave his blanket to Charlie Brown, on another occasion, Lucy snatched his blanket away and buried it in an effort to break Linus of his habit. Linus literally dug up the neighborhood for days trying to find it until Snoopy finally dug it up. Possession of the blanket is often sought by Snoopy, who has used many tricks and subterfuges to relieve Linus of it, even at one point having the blanket delivered to his doghouse. Snoopy commonly runs up, quickly grabs the blanket in his mouth, and drags Linus along with it, then swings him, once, Linus was so angry at Snoopy for snatching his blanket again and again that he retaliated by threatening Snoopys supper dish. Upon hearing that Linus had possession of his most prized possession, Snoopy gave Linus back the blanket fairly quickly, thinking, I never dreamed he would fight so dirty
31.
Peanuts
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Peanuts is a syndicated daily and Sunday American comic strip written and illustrated by Charles M. Schulz, which ran from October 2,1950, to February 13,2000, continuing in reruns afterward. The comic strip is the most popular and influential in the history of comic strips, with 17,897 strips published in all, making it arguably the longest story ever told by one human being. At its peak, Peanuts ran in over 2,600 newspapers, with a readership of 355 million in 75 countries and it helped to cement the four-panel gag strip as the standard in the United States, and together with its merchandise earned Schulz more than $1 billion. Reprints of the strip are still syndicated and run in almost every U. S. newspaper, the strip focuses entirely on a social circle of young children, where adults exist but are never seen or heard. The main character, Charlie Brown, is meek, nervous and he is unable to fly a kite, win a baseball game, or kick a football. Peanuts is one of the strips with philosophical, psychological. The strips humor is psychologically complex, and the characters interactions formed a tangle of relationships that drove the strip, the holiday specials remain popular and are currently broadcast on ABC in the U. S. during the corresponding seasons. The Peanuts franchise met acclaim in theatre, with the stage musical Youre a Good Man, Charlie Brown being a successful, in 2013, TV Guide ranked the Peanuts television specials the fourth Greatest TV Cartoon of All Time. A computer-animated feature film based on the strip, The Peanuts Movie, was released on November 6,2015, Peanuts had its origin in Lil Folks, a weekly panel comic that appeared in Schulzs hometown paper, the St. Paul Pioneer Press, from 1947 to 1950. He first used the name Charlie Brown for a character there, the series also had a dog that looked much like the early 1950s version of Snoopy. In 1948, Schulz sold a cartoon to The Saturday Evening Post which published 17 single-panel cartoons by Schulz, the first of these was of a boy sitting with his feet on an ottoman. In 1948, Schulz tried to have Lil Folks syndicated through the Newspaper Enterprise Association, Schulz would have been an independent contractor for the syndicate, unheard of in the 1940s, but the deal fell through. Lil Folks was dropped in early 1950, later that year, Schulz approached the United Feature Syndicate - also operated by Scripps-Howard - with his best work from Lil Folks. When his work was picked up by United Feature Syndicate, they decided to run the new comic strip he had working on. This strip was similar in spirit to the comic, but it had a set cast of characters. The name Lil Folks was too close to the names of two comics of the time, Al Capps Lil Abner and a strip titled Little Folks. To avoid confusion, the settled on the name Peanuts. Peanuts was a title Schulz always disliked, in a 1987 interview, Schulz said of the title Peanuts, Its totally ridiculous, has no meaning, is simply confusing, and has no dignity—and I think my humor has dignity
32.
90 Antiope
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90 Antiope is a double asteroid in the outer asteroid belt. It was discovered on October 1,1866, by Robert Luther, in 2000, it was found to consist of two almost-equally-sized bodies orbiting each other. At average diameters of about 88 km and 84 km, both components are among the 500 largest asteroids, Antiope is a member of the Themis family of asteroids that share similar orbital elements. The number in 90 Antiopes name denotes that it was the 90th asteroid to be discovered and its proper name comes from Greek mythology, but it is disputed whether this is Antiope the Amazon or Antiope the mother of Amphion and Zethus. However, the name Antiope is also used to refer to the system as a whole. The most remarkable feature of Antiope is that it consists of two components of almost equal size, making it a double asteroid. Its binary nature was discovered on 10 August 2000 by a group of astronomers using adaptive optics at the Keck Telescope on Mauna Kea, before this, IRAS observations had suggested that the asteroid was 120 km in diameter. Antiope orbits in the third of the core region of the asteroid belt. Since each component is about 86±1 km across, with their centers separated by only about 171 kilometers, as a result, the two bodies orbit around the common center of mass which lies in the space between them. The orbital period is approximately 16.50 hours, and the eccentricity below 0.006, every several years, a period of mutual occultations occurs when the asteroid is viewed from Earth. Using Keplers third law, the mass and density of the components can be derived from the orbital period, the axis of the mutual orbit of the two components points towards ecliptic coordinates = with 2 degrees uncertainty. This is tilted about 63° to the orbit of the system. Antiope itself has an diameter of about 88 km, while its twin. Like most bodies in this region, the components of the Antiope system are of the dark C spectral type, the shape model is consistent with slightly non-spherical components, having a size ratio of 0.95, and exhibiting equilibrium figures for homogeneous rotating bodies. A comparison with grazing occultation event lightcurves taken in 2003 suggests that the shape of the components do not depart much from Roche equilibrium figures. The impactor is calculated to have more than 17 km in diameter. The crater can not be resolved using the W. M. Keck II telescope, another observed stellar occultation by Antiope was reported on June 11,1980. Discovery of Companions to Asteroids 762 Pulcova and 90 Antiope SWrI Press Release, an Occultation by the double asteroid Antiope seen in California Beatty, Kelly
33.
Precession
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Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, in other words, if the axis of rotation of a body is itself rotating about a second axis, that body is said to be precessing about the second axis. A motion in which the second Euler angle changes is called nutation, in physics, there are two types of precession, torque-free and torque-induced. In astronomy, precession refers to any of several changes in an astronomical bodys rotational or orbital parameters. An important example is the change in the orientation of the axis of rotation of the Earth. Torque-free precession implies that no moment is applied to the body. In torque-free precession, the momentum is a constant. What makes this possible is a moment of inertia, or more precisely. The inertia matrix is composed of the moments of inertia of a body calculated with respect to coordinate axes. If an object is asymmetric about its axis of rotation. The result is that the component of the velocities of the body about each axis will vary inversely with each axis moment of inertia. When an object is not perfectly solid, internal vortices will tend to damp torque-free precession, R new = exp R old for the skew-symmetric matrix ×. Torque-induced precession is the phenomenon in which the axis of a spinning object describes a cone in space when a torque is applied to it. The phenomenon is seen in a spinning toy top. If the speed of the rotation and the magnitude of the external torque are constant, the spin axis will move at right angles to the direction that would intuitively result from the external torque. In the case of a toy top, its weight is acting downwards from its center of mass and these two opposite forces produce a torque which causes the top to precess. The device depicted on the right is gimbal mounted, from inside to outside there are three axes of rotation, the hub of the wheel, the gimbal axis, and the vertical pivot. To distinguish between the two axes, rotation around the wheel hub will be called spinning, and rotation around the gimbal axis will be called pitching
34.
Impact event
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An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have found to regularly occur in planetary systems, though the most frequent involve asteroids. Impact craters and structures are dominant landforms on many of the Solar Systems solid objects and present the strongest empirical evidence for their frequency, Impact events appear to have played a significant role in the evolution of the Solar System since its formation. Notable impact events include the Chicxulub impact,66 million years ago, throughout recorded history, hundreds of Earth impacts have been reported, with some occurrences causing deaths, injuries, property damage, or other significant localised consequences. One of the best-known recorded impacts in modern times was the Tunguska event, the Comet Shoemaker–Levy 9 impact provided the first direct observation of an extraterrestrial collision of Solar System objects, when the comet broke apart and collided with Jupiter in July 1994. Impact events have been a plot and background element in science fiction, Impact structures are the result of impact events on solid objects and, as the dominant landforms on many of the Systems solid objects, present the most solid evidence of prehistoric events. Small objects frequently collide with Earth, there is an inverse relationship between the size of the object and the frequency of such events. The lunar cratering record shows that the frequency of impacts decreases as approximately the cube of the craters diameter. Asteroids with a 1 km diameter strike Earth every 500,000 years on average, large collisions – with 5 km objects – happen approximately once every twenty million years. The last known impact of an object of 10 km or more in diameter was at the Cretaceous–Paleogene extinction event 66 million years ago, the energy released by an impactor depends on diameter, density, velocity, and angle. The diameter of most near-Earth asteroids that have not been studied by radar or infrared can generally only be estimated within about a factor of 2 based on the asteroid brightness, the density is generally assumed because the diameter and mass are also generally estimates. The minimum impact velocity on Earth is 11 km/s with asteroid impacts averaging around 17 km/s, the most probable impact angle is 45 degrees. Stony asteroids with a diameter of 4 meters enter Earths atmosphere approximately once per year. Asteroids with a diameter of 7 meters enter the atmosphere about every 5 years with as much energy as the atomic bomb dropped on Hiroshima. These ordinarily explode in the atmosphere and most or all of the solids are vaporized. However, asteroids with a diameter of 20 m, and which strike Earth approximately twice every century, the 2013 Chelyabinsk meteor was estimated to be about 20 m in diameter with an airburst of around 500 kilotons, an explosion 30 times the one over Hiroshima. Much larger objects may impact the solid earth and create a crater, objects with a diameter less than 1 m are called meteoroids and seldom make it to the ground to become meteorites. Although no human is known to have been killed directly by an impact, in 2005 it was estimated that the chance of a single person born today dying due to an impact is around 1 in 200,000
35.
Collision
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A collision or crash is an event in which two or more bodies exert forces on each other for a relatively short time. Some examples of interactions that scientists would consider collisions, An insect touches its antenna to the leaf of a plant. The antenna is said to collide with leaf, a cat walks delicately through the grass. Each contact that its paws make with the ground is a collision, each brush of its fur against a blade of grass is a collision. When a boxer throws a punch, his fist is said to collide with the opponents face, the magnitude of the velocity difference just before impact is called the closing speed. What distinguishes different types of collisions is whether they also conserve kinetic energy, the Line of impact is the line which is collinear to the common normal of the surfaces that are closest or in contact during impact. This is the line along which internal force of collision acts during impact, specifically, collisions can either be elastic, meaning they conserve both momentum and kinetic energy, or inelastic, meaning they conserve momentum but not kinetic energy. An inelastic collision is sometimes called a plastic collision. A “perfectly inelastic” collision is a case of inelastic collision in which the two bodies stick together after impact. The degree to which a collision is elastic or inelastic is quantified by the coefficient of restitution, a perfectly elastic collision has a coefficient of restitution of one, a perfectly inelastic collision has a coefficient of restitution of zero. In reality, any macroscopic collision between objects will convert some kinetic energy to internal energy and other forms of energy, so no large-scale impacts are perfectly elastic, however, some problems are sufficiently close to perfectly elastic that they can be approximated as such. In this case, the coefficient of restitution equals one, an inelastic collision is one in which part of the kinetic energy is changed to some other form of energy in the collision. Momentum is conserved in collisions, but one cannot track the kinetic energy through the collision since some of it is converted to other forms of energy. In this case, coefficient of restitution does not equal one, collisions in ideal gases approach perfectly elastic collisions, as do scattering interactions of sub-atomic particles which are deflected by the electromagnetic force. Some large-scale interactions like the slingshot type gravitational interactions between satellites and planets are perfectly elastic, collisions between hard spheres may be nearly elastic, so it is useful to calculate the limiting case of an elastic collision. The assumption of conservation of momentum as well as the conservation of kinetic energy makes possible the calculation of the velocities in two-body collisions. In maritime law, it is desirable to distinguish between the situation of a vessel striking a moving object, and that of it striking a stationary object. The word allision is then used to mean the striking of a stationary object, relatively few problems involving collisions can be solved analytically, the remainder require numerical methods
. Bibcode:2008Icar..196..578D. doi:10.1016/j.icarus.2008.03.014.
