1.
Karl Theodor Robert Luther
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Karl Theodor Robert Luther, normally published as Robert Luther, was a German astronomer. While working at the Bilk Observatory in Düsseldorf, Germany, he searched for asteroids, two of his discoveries are now known to have unusual properties,90 Antiope, a binary asteroid with equal components, and the extremely slow-rotating 288 Glauke. The asteroid 1303 Luthera and the lunar crater Luther were named in his honour and he was awarded the Lalande Prize in 1852,1855,1860, and 1861
2.
Proserpina
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Proserpina or Proserpine is an ancient Roman goddess whose cult, myths and mysteries were based on those of Greek Persephone and her mother Demeter, the Greek goddess of grain and agriculture. The Romans identified Proserpina with their native fertility goddess Libera, daughter of the grain and agriculture goddess Ceres, just as Persephone was thought to be a daughter of Demeter, Romans made Proserpina a daughter of Demeters Roman equivalent, Ceres. Her name is a Latinisation of Persephone, perhaps influenced by the Latin proserpere, the cult originated in southern Italy and was probably based on the women-only Greek Thesmophoria, a mystery cult to Demeter and Persephone as Mother and Maiden. It arrived along with its Greek priestesses, who were granted Roman citizenship so that they could pray to the gods with a foreign and external knowledge and their joint cult recalls Demeters search for Persephone, after the latters rape and abduction into the underworld by Hades. At the Aventine, the new cult took its place alongside the old and it made no reference to Liber, whose open and gender-mixed cult continued to play a central role in plebeian culture, as a patron and protector of plebeian rights, freedoms and values. Unmarried girls should emulate the chastity of Proserpina, the maiden, married women should seek to emulate Ceres and their rites were intended to secure a good harvest, and increase the fertility of those who partook in the mysteries. A Temple of Proserpina was located in a suburb of Melite, in modern Mtarfa, the temples ruins were quarried between the 17th and 18th centuries, and only a few fragments survive. The best-known myth surrounding Proserpina is of her abduction by the god of the Underworld, her mother Ceres frantic search for her, renamed thus, the king of the underworld is distanced from his consorts violent abduction. In the early 1st century Ovid gives two versions of the myth in Latin, one in Book 5 of his Metamorphoses. Venus, in order to bring love to Pluto, sent her son Amor to hit Pluto with one of his arrows and he abducted her in order to marry her and live with her in the underworld of which he was the ruler. In her desperation Ceres angrily stopped the growth of fruits and vegetables, Ceres refused to go back to Mount Olympus and started walking on the Earth, making a desert at every step. Worried, Jupiter sent Mercury to order Pluto to free Proserpina, Pluto obeyed, but before letting her go he made her eat six pomegranate seeds, because those who have eaten the food of the dead could not return to the world of the living. This meant that she would have to live six months of year with him. In another version of the story, Proserpina ate only four pomegranate seeds, when Jupiter ordered her return, Pluto struck a deal with Jupiter, saying that since she had stolen his pomegranate seeds, she must stay with him four months of the year in return. For this reason, in spring when Ceres receives her back, the crops blossom. In the autumn Ceres changes the leaves to shades of brown, during the time that Proserpina resides with Pluto, the world goes through winter, a time when the earth is barren. The most extensive myth of Proserpina in Latin is Claudians and it is closely connected with that of Orpheus and Eurydice. But Orpheus could not resist a backward glance, so Eurydice was forever lost to him
3.
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
4.
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
5.
Perihelion and aphelion
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The perihelion is the point in the orbit of a celestial body where it is nearest to its orbital focus, generally a star. It is the opposite of aphelion, which is the point in the orbit where the body is farthest from its focus. The word perihelion stems from the Ancient Greek words peri, meaning around or surrounding, aphelion derives from the preposition apo, meaning away, off, apart. According to Keplers first law of motion, all planets, comets. Hence, a body has a closest and a farthest point from its parent object, that is, a perihelion. Each extreme is known as an apsis, orbital eccentricity measures the flatness of the orbit. Because of the distance at aphelion, only 93. 55% of the solar radiation from the Sun falls on a given area of land as does at perihelion. However, this fluctuation does not account for the seasons, as it is summer in the northern hemisphere when it is winter in the southern hemisphere and vice versa. Instead, seasons result from the tilt of Earths axis, which is 23.4 degrees away from perpendicular to the plane of Earths orbit around the sun. Winter falls on the hemisphere where sunlight strikes least directly, and summer falls where sunlight strikes most directly, in the northern hemisphere, summer occurs at the same time as aphelion. Despite this, there are larger land masses in the northern hemisphere, consequently, summers are 2.3 °C warmer in the northern hemisphere than in the southern hemisphere under similar conditions. Apsis Ellipse Solstice Dates and times of Earths perihelion and aphelion, 2000–2025 from the United States Naval Observatory
6.
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
7.
Astronomical unit
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The astronomical unit is a unit of length, roughly the distance from Earth to the Sun. However, that varies as Earth orbits the Sun, from a maximum to a minimum. Originally conceived as the average of Earths aphelion and perihelion, it is now defined as exactly 149597870700 metres, the astronomical unit is used primarily as a convenient yardstick for measuring distances within the Solar System or around other stars. However, it is also a component in the definition of another unit of astronomical length. A variety of symbols and abbreviations have been in use for the astronomical unit. In a 1976 resolution, the International Astronomical Union used the symbol A for the astronomical unit, in 2006, the International Bureau of Weights and Measures recommended ua as the symbol for the unit. In 2012, the IAU, noting that various symbols are presently in use for the astronomical unit, in the 2014 revision of the SI Brochure, the BIPM used the unit symbol au. In ISO 80000-3, the symbol of the unit is ua. Earths orbit around the Sun is an ellipse, the semi-major axis of this ellipse is defined to be half of the straight line segment that joins the aphelion and perihelion. The centre of the sun lies on this line segment. In addition, it mapped out exactly the largest straight-line distance that Earth traverses over the course of a year, knowing Earths shift and a stars shift enabled the stars distance to be calculated. But all measurements are subject to some degree of error or uncertainty, improvements in precision have always been a key to improving astronomical understanding. Improving measurements were continually checked and cross-checked by means of our understanding of the laws of celestial mechanics, the expected positions and distances of objects at an established time are calculated from these laws, and assembled into a collection of data called an ephemeris. NASAs Jet Propulsion Laboratory provides one of several ephemeris computation services, in 1976, in order to establish a yet more precise measure for the astronomical unit, the IAU formally adopted a new definition. Equivalently, by definition, one AU is the radius of an unperturbed circular Newtonian orbit about the sun of a particle having infinitesimal mass. As with all measurements, these rely on measuring the time taken for photons to be reflected from an object. However, for precision the calculations require adjustment for such as the motions of the probe. In addition, the measurement of the time itself must be translated to a scale that accounts for relativistic time dilation
8.
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
9.
Mean anomaly
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In celestial mechanics, the mean anomaly is an angle used in calculating the position of a body in an elliptical orbit in the classical two-body problem. Define T as the time required for a body to complete one orbit. In time T, the radius vector sweeps out 2π radians or 360°. The average rate of sweep, n, is then n =2 π T or n =360 ∘ T, define τ as the time at which the body is at the pericenter. From the above definitions, a new quantity, M, the mean anomaly can be defined M = n, because the rate of increase, n, is a constant average, the mean anomaly increases uniformly from 0 to 2π radians or 0° to 360° during each orbit. It is equal to 0 when the body is at the pericenter, π radians at the apocenter, if the mean anomaly is known at any given instant, it can be calculated at any later instant by simply adding n δt where δt represents the time difference. Mean anomaly does not measure an angle between any physical objects and it is simply a convenient uniform measure of how far around its orbit a body has progressed since pericenter. The mean anomaly is one of three parameters that define a position along an orbit, the other two being the eccentric anomaly and the true anomaly. Define l as the longitude, the angular distance of the body from the same reference direction. Thus mean anomaly is also M = l − ϖ, mean angular motion can also be expressed, n = μ a 3, where μ is a gravitational parameter which varies with the masses of the objects, and a is the semi-major axis of the orbit. Mean anomaly can then be expanded, M = μ a 3, and here mean anomaly represents uniform angular motion on a circle of radius a
10.
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
11.
Longitude of the ascending node
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The longitude of the ascending node is one of the orbital elements used to specify the orbit of an object in space. It is the angle from a direction, called the origin of longitude, to the direction of the ascending node. The ascending node is the point where the orbit of the passes through the plane of reference. Commonly used reference planes and origins of longitude include, For a geocentric orbit, Earths equatorial plane as the plane. In this case, the longitude is called the right ascension of the ascending node. The angle is measured eastwards from the First Point of Aries to the node, for a heliocentric orbit, the ecliptic as the reference plane, and the First Point of Aries as the origin of longitude. The angle is measured counterclockwise from the First Point of Aries to the node, the angle is measured eastwards from north to the node. pp.40,72,137, chap. In the case of a star known only from visual observations, it is not possible to tell which node is ascending. In this case the orbital parameter which is recorded is the longitude of the node, Ω, here, n=<nx, ny, nz> is a vector pointing towards the ascending node. The reference plane is assumed to be the xy-plane, and the origin of longitude is taken to be the positive x-axis, K is the unit vector, which is the normal vector to the xy reference plane. For non-inclined orbits, Ω is undefined, for computation it is then, by convention, set equal to zero, that is, the ascending node is placed in the reference direction, which is equivalent to letting n point towards the positive x-axis. Kepler orbits Equinox Orbital node perturbation of the plane can cause revolution of the ascending node
12.
Argument of periapsis
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The argument of periapsis, symbolized as ω, is one of the orbital elements of an orbiting body. Parametrically, ω is the angle from the ascending node to its periapsis. For specific types of orbits, words such as perihelion, perigee, periastron, an argument of periapsis of 0° means that the orbiting body will be at its closest approach to the central body at the same moment that it crosses the plane of reference from South to North. An argument of periapsis of 90° means that the body will reach periapsis at its northmost distance from the plane of reference. Adding the argument of periapsis to the longitude of the ascending node gives the longitude of the periapsis, however, especially in discussions of binary stars and exoplanets, the terms longitude of periapsis or longitude of periastron are often used synonymously with argument of periapsis. In the case of equatorial orbits, the argument is strictly undefined, where, ex and ey are the x- and y-components of the eccentricity vector e. In the case of circular orbits it is assumed that the periapsis is placed at the ascending node. Kepler orbit Orbital mechanics Orbital node
13.
IRAS
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The Infrared Astronomical Satellite was the first-ever space telescope to perform a survey of the entire night sky at infrared wavelengths. Launched on 25 January 1983, its mission lasted ten months, the telescope was a joint project of the United States, the Netherlands, and the United Kingdom. Over 250,000 infrared sources were observed at 12,25,60, support for the processing and analysis of data from IRAS was contributed from the Infrared Processing and Analysis Center at the California Institute of Technology. Currently, the Infrared Science Archive at IPAC holds the IRAS archive, the success of early infrared space astronomy led to further missions, such as the Infrared Space Observatory and the Hubble Space Telescopes NICMOS instrument. IRAS was the first observatory to perform a survey at infrared wavelengths. It mapped 96% of the sky four times, at 12,25,60 and 100 micrometers and it discovered about 350,000 sources, many of which are still awaiting identification. About 75,000 of those are believed to be starburst galaxies, many other sources are normal stars with disks of dust around them, possibly the early stage of planetary system formation. New discoveries included a dust disk around Vega and the first images of the Milky Ways core, IRASs life, like that of most infrared satellites that followed, was limited by its cooling system. To effectively work in the domain, a telescope must be cooled to cryogenic temperatures. In IRASs case,73 kilograms of superfluid helium kept the telescope at a temperature of 2 K, the on-board supply of liquid helium was depleted after 10 months on 21 November 1983, causing the telescope temperature to rise, preventing further observations. The spacecraft continues to orbit the Earth, IRAS was designed to catalog fixed sources, so it scanned the same region of sky several times. Jack Meadows led a team at Leicester University, including John Davies and Simon Green and this led to the discovery of three asteroids, including 3200 Phaethon, six comets, and a huge dust trail associated with comet 10P/Tempel. The comets included 126P/IRAS, 161P/Hartley–IRAS, and comet IRAS–Araki–Alcock, which made an approach to the Earth in 1983. Out of the six comets IRAS found, four were long period, further analysis revealed that, of several unidentified objects, nine were distant galaxies and the tenth was intergalactic cirrus. None were found to be Solar System bodies, during its mission, IRAS detected odd infrared signatures around several stars. This led to the systems being targeted by the Hubble Space Telescopes NICMOS instrument between 1999 and 2006, but nothing was detected, in 2014, using new image processing techniques on the Hubble data, researchers discovered planetary disks around these stars. A next generation of infrared space telescopes began when NASAs Wide-field Infrared Survey Explorer launched on 14 December 2009 aboard a Delta II rocket from Vandenberg Air Force Base. A. Neugebauer, G. Habing, H. J. Clegg, P. E. Chester, Infrared Astronomical Satellite, Catalogs and Atlases
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.
S-type asteroid
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S-type asteroids, or silicaceous asteroids, are of a stony composition, hence the name. Approximately 17% of asteroids are of type, making it the second most common after the C-type. S-types are moderately bright and consist mainly of iron- and magnesium-silicates and they are dominant in the inner asteroid belt within 2.2 AU, common in the central belt within about 3 AU, but become rare farther out. The largest is 15 Eunomia, with the next largest members by diameter being 3 Juno,29 Amphitrite,532 Herculina and 7 Iris. Their spectrum has a steep slope at wavelengths shorter than 0.7 µm. The 1 µm absorption is indicative of the presence of silicates, often there is also a broad but shallow absorption feature centered near 0.63 µm. The composition of asteroids is similar to a variety of stony meteorites which share similar spectral characteristics. This whole S assemblage of asteroids is spectrally quite distinct from the carbonaceous C-group, Asteroid spectral types L-type asteroid K-type asteroid X-type asteroid Bus, S. J. Binzel, R. P. Phase II of the Small Main-belt Asteroid Spectroscopy Survey, A feature-based taxonomy
17.
Asteroid
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Asteroids are minor planets, especially those of the inner Solar System. The larger ones have also been called planetoids and these terms have historically been applied to any astronomical object orbiting the Sun that did not show the disc of a planet and was not observed to have the characteristics of an active comet. As minor planets in the outer Solar System were discovered and found to have volatile-based surfaces that resemble those of comets, in this article, the term asteroid refers to the minor planets of the inner Solar System including those co-orbital with Jupiter. There are millions of asteroids, many thought to be the remnants of planetesimals. The large majority of known asteroids orbit in the belt between the orbits of Mars and Jupiter, or are co-orbital with Jupiter. However, other orbital families exist with significant populations, including the near-Earth objects, individual asteroids are classified by their characteristic spectra, with the majority falling into three main groups, C-type, M-type, and S-type. These were named after and are identified with carbon-rich, metallic. The size of asteroids varies greatly, some reaching as much as 1000 km across, asteroids are differentiated from comets and meteoroids. In the case of comets, the difference is one of composition, while asteroids are composed of mineral and rock, comets are composed of dust. In addition, asteroids formed closer to the sun, preventing the development of the aforementioned cometary ice, the difference between asteroids and meteoroids is mainly one of size, meteoroids have a diameter of less than one meter, whereas asteroids have a diameter of greater than one meter. Finally, meteoroids can be composed of either cometary or asteroidal materials, only one asteroid,4 Vesta, which has a relatively reflective surface, is normally visible to the naked eye, and this only in very dark skies when it is favorably positioned. Rarely, small asteroids passing close to Earth may be visible to the eye for a short time. As of March 2016, the Minor Planet Center had data on more than 1.3 million objects in the inner and outer Solar System, the United Nations declared June 30 as International Asteroid Day to educate the public about asteroids. The date of International Asteroid Day commemorates the anniversary of the Tunguska asteroid impact over Siberia, the first asteroid to be discovered, Ceres, was found in 1801 by Giuseppe Piazzi, and was originally considered to be a new planet. In the early half of the nineteenth century, the terms asteroid. Asteroid discovery methods have improved over the past two centuries. This task required that hand-drawn sky charts be prepared for all stars in the band down to an agreed-upon limit of faintness. On subsequent nights, the sky would be charted again and any moving object would, hopefully, the expected motion of the missing planet was about 30 seconds of arc per hour, readily discernible by observers
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Roman mythology
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Roman mythology is the body of traditional stories pertaining to ancient Romes legendary origins and religious system, as represented in the literature and visual arts of the Romans. Roman mythology may also refer to the study of these representations. The Romans usually treated their traditional narratives as historical, even when these have miraculous or supernatural elements, the stories are often concerned with politics and morality, and how an individuals personal integrity relates to his or her responsibility to the community or Roman state. When the stories illuminate Roman religious practices, they are concerned with ritual, augury. Romes early myths and legends also have a relationship with Etruscan religion. In particular, the versions of Greek myths in Ovids Metamorphoses, written during the reign of Augustus, because ritual played the central role in Roman religion that myth did for the Greeks, it is sometimes doubted that the Romans had much of a native mythology. This perception is a product of Romanticism and the scholarship of the 19th century. From the Renaissance to the 18th century, however, Roman myths were an inspiration particularly for European painting, the Roman tradition is rich in historical myths, or legends, concerning the foundation and rise of the city. These narratives focus on human actors, with only occasional intervention from deities, in Romes earliest period, history and myth have a mutual and complementary relationship. As T. P. Wiseman notes, The Roman stories still matter, as they mattered to Dante in 1300 and Shakespeare in 1600, what does it take to be a free citizen. Can a superpower still be a republic, how does well-meaning authority turn into murderous tyranny. Major sources for Roman myth include the Aeneid of Vergil and the first few books of Livys history as well as Dionysius s Roman Antiquities. Other important sources are the Fasti of Ovid, a six-book poem structured by the Roman religious calendar, scenes from Roman myth also appear in Roman wall painting, coins, and sculpture, particularly reliefs. The Aeneid and Livys early history are the best extant sources for Romes founding myths, material from Greek heroic legend was grafted onto this native stock at an early date. By extension, the Trojans were adopted as the ancestors of the Roman people. Rape of the Sabine women, explaining the importance of the Sabines in the formation of Roman culture, numa Pompilius, the Sabine second king of Rome who consorted with the nymph Egeria and established many of Romes legal and religious institutions. Servius Tullius, the king of Rome, whose mysterious origins were freely mythologized. The Tarpeian Rock, and why it was used for the execution of traitors, lucretia, whose self-sacrifice prompted the overthrow of the early Roman monarchy and led to the establishment of the Republic
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Goddess
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A goddess is a female deity in polytheistic religions. Goddesses most often have characteristics that are apotheosize in their pure form. However, in some cases goddesses may embody neutral forms personifying both male and female characteristics, or they may even exhibit traits that are associated with the male gender. In some faiths, a female figure holds a central place in religious prayer. For example, Shaktism, the worship of the force that animates the world, is one of the three major sects of Hinduism. Polytheist religions, including Polytheistic reconstructionists, honour multiple goddesses and gods and these deities may be part of a pantheon, or different regions may have tutelary deities. The reconstructionists, like their ancient forebears, honour the deities particular to their country of origin, the noun goddess is a secondary formation, combining the Germanic god with the Latinate -ess suffix. It first appeared in Middle English, from about 1350, the English word follows the linguistic precedent of a number of languages—including Egyptian, Classical Greek, and several Semitic languages—that add a feminine ending to the languages word for god. Joseph Campbell in The Power of Myth, a 1988 interview with Bill Moyers, links the image of the Earth or Mother Goddess to symbols of fertility and reproduction. For example, Campbell states that, There have been systems of religion where the mother is the prime parent, and in Egypt you have the Mother Heavens, the Goddess Nut, who is represented as the whole heavenly sphere. Joseph Campbell, Well that was associated primarily with agriculture and the agricultural societies and it has to do with the earth. The human woman gives birth just as the earth gives birth to the plants. so woman magic, and the personification of the energy that gives birth to forms and nourishes forms is properly female. It is in the world of ancient Mesopotamia, the Egyptian Nile. Campbell also argues that the image of the Virgin Mary was derived from the image of Isis and her child Horus, other Mesopotamian goddesses include Ninhursag, Ninlil, Antu, Gaga Goddesses of the Canaanite religion, Baalat Gebal, Astarte, Anat. Cybele, Her Hittite name was Kubaba, but her name changed to Cybele in Phrygian and Roman culture and her effect can be also seen on Artemis as the Lady of Ephesus. Hebat, Mother Goddess of the Hittite pantheon and wife of the sky god. She was the origin of the Hurrian cult, arinniti, Hittite Goddess of the sun. She became patron of the Hittite Empire and monarchy, leto, A mother Goddess figure in Lykia
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Ceres (mythology)
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In ancient Roman religion, Ceres was a goddess of agriculture, grain crops, fertility and motherly relationships. She was originally the central deity in Romes so-called plebeian or Aventine Triad and her seven-day April festival of Cerealia included the popular Ludi Ceriales. She was also honoured in the May lustratio of the fields at the Ambarvalia festival, at harvest-time, Ceres is the only one of Romes many agricultural deities to be listed among the Dii Consentes, Romes equivalent to the Twelve Olympians of Greek mythology. The Romans saw her as the counterpart of the Greek goddess Demeter, whose mythology was reinterpreted for Ceres in Roman art and literature. Roman etymologists thought ceres derived from the Latin verb gerere, to bear, bring forth, produce, because the goddess was linked to pastoral, agricultural and human fertility. Archaic cults to Ceres are well-evidenced among Romes neighbours in the Regal period, including the ancient Latins, Oscans and Sabellians, an archaic Faliscan inscription of c.600 BC asks her to provide far, which was a dietary staple of the Mediterranean world. Throughout the Roman era, Ceres name was synonymous with grain and, by extension and she had the power to fertilise, multiply and fructify plant and animal seed, and her laws and rites protected all activities of the agricultural cycle. In January, Ceres was offered spelt wheat and a pregnant sow and this was almost certainly held before the annual sowing of grain. The divine portion of sacrifice was the entrails presented in an earthenware pot, in a rural context, Cato the Elder describes the offer to Ceres of a porca praecidanea. Before the harvest, she was offered a propitiary grain sample, Ovid tells that Ceres is content with little, provided that her offerings are casta. Ceres main festival, Cerealia, was held from mid to late April and it was organised by her plebeian aediles and included circus games. From c.175 BC, Cerealia included ludi scaenici through April 12 to 18, W. H. Roscher lists these deities among the indigitamenta, names used to invoke specific divine functions. The adult males of the party waited at the grooms house. A wedding sacrifice was offered to Tellus on the brides behalf, Varro describes the sacrifice of a pig as a worthy mark of weddings because our women, and especially nurses call the female genitalia porcus. Spaeth believes Ceres may have included in the sacrificial dedication, because she is closely identified with Tellus and, as Ceres legifera. In the most solemn form of marriage, confarreatio, the bride and groom shared a cake made of far, from at least the mid-republican era, an official, joint cult to Ceres and Proserpina reinforced Ceres connection with Roman ideals of female virtue. The promotion of this cult coincides with the rise of a nobility, an increased birthrate among plebeian commoners. Several of Ceres ancient Italic precursors are connected to fertility and motherhood
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Underworld
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The underworld or netherworld is an otherworld thought to be deep underground or beneath the surface of the world in most religions and mythologies. Typically it is a place where the souls of the departed go, chthonic is the technical adjective for things of the underworld. This list includes underworlds in mythology, with links to corresponding articles. This list includes rulers or guardians of the underworld in various mythologies, otherworld World Tree — A tree that connects the heavens, the earth, and the underworld in a number of spiritual belief systems
22.
Terre Haute, Indiana
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Terre Haute is a city in and the county seat of Vigo County, Indiana, United States, near the states western border with Illinois. As of the 2010 census, the city had a population of 60,785. Located along the Wabash River, Terre Haute is the capital of the Wabash Valley. The city is home to higher education institutions, including Indiana State University, Saint Mary-of-the-Woods College. Terre Haute is notable for being the home of Socialist Party of America leader and five-time presidential nominee, Debs and the Federal Correctional Complex. Terre Haute is located alongside the bank of the Wabash River in western Indiana. The city lies about 75 miles west of Indianapolis, according to the 2010 census, Terre Haute has a total area of 35.272 square miles, of which 34.54 square miles is land and 0.732 square miles is water. The Wabash River dominates the geography of the city, forming its western border. Small bluffs on the east side of city mark the edge of the flood plain. Lost Creek and Honey Creek drain the northern and southern sections of the city, in the late 19th century, several oil and mineral wells were productive in and near the center of the city. That well produced oil into the 1920s, Terre Haute is at the intersection of two major roadways, U. S.40 from California to Maryland and US41 from Copper Harbor, Michigan to Miami, Florida. Terre Haute is located 77 miles southwest of Indianapolis and within 185 miles of Chicago, St. Louis, Louisville, Climate is characterized by relatively high temperatures and evenly distributed precipitation throughout the year. The Köppen Climate Classification subtype for this climate is Dfa, Terre Hautes name was derived from the French phrase terre haute, meaning Highland. It was likely named by French explorers in the area in the early 18th century to describe the unique location above the Wabash River, at the time the area was claimed by the French and British, these highlands were considered the border between Canada and Louisiana. The construction of Fort Harrison in 1811 marked the beginning of a permanent population of European-Americans. A Wea Indian village already existed near the fort, and the orchards, the village of Terre Haute, then a part of Knox County, Indiana, was platted in 1816. Growth really began when the founders won the bid to make it the county seat when Vigo County was formed in March 1818. When the villages 1,000 residents voted to incorporate in 1832, Terre Haute became a town, early Terre Haute was a center of farming, milling and pork processing
23.
Light curve
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In astronomy, a light curve is a graph of light intensity of a celestial object or region, as a function of time. The light is usually in a particular frequency interval or band, the study of the light curve, together with other observations, can yield considerable information about the physical process that produces it or constrain the physical theories about it. Light waves can also be used in botany to determine a plants reactions to light intensities, in astronomy, light curves from a supernova are used to determine what type of supernova it is. If the supernovas light curve has a maximum and slopes down gradually. If the supernovas light curve has a sharp maximum, slopes down quickly. In planetary science, a curve can be used to derive the rotation period of a minor planet, moon. Thus, astronomers measure the amount of produced by an object as a function of time. The time separation of peaks in the curve gives an estimate of the rotational period of the object. The difference between the maximum and minimum brightnesses can be due to the shape of the object, or to bright, for example, an asymmetrical asteroids light curve generally has more pronounced peaks, while a more spherical objects light curve will be flatter. The Asteroid Lightcurve Database of the Collaborative Asteroid Lightcurve Link uses a code to assess the quality of a period solution for minor planet light curves. Its quality code parameter U ranges from 0 to 3, U =0 → Result later proven incorrect U =1 → Result based on fragmentary light curve, U =2 → Result based on less than full coverage. Period may be wrong by 30 percent or ambiguous, U =3 → Secure result within the precision given. A trailing plus sign or minus sign is used to indicate a slightly better or worse quality than the unsigned value. In botany, a light curve shows the response of leaf tissue or algal communities to varying light intensities. Since photosynthesis is limited by ambient carbon dioxide levels, light curves are often repeated at several different constant carbon dioxide concentrations. The AAVSO online light curve generator can plot light curves for thousands of variable stars Lightcurves, An Introduction by NASAs Imagine the Universe
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Magnitude (astronomy)
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In astronomy, magnitude is a logarithmic measure of the brightness of an object, measured in a specific wavelength or passband, usually in the visible or near-infrared spectrum. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus, astronomers use two different definitions of magnitude, apparent magnitude and absolute magnitude. This distance is 10 parsecs for stars and 1 astronomical unit for planets, a minor planets size is typically estimated based on its absolute magnitude in combination with its presumed albedo. The brighter an object appears, the lower the value of its magnitude, with the brightest objects reaching negative values. The Sun has an apparent magnitude of −27, the full moon −13, the brightest planet Venus measures −5, and Sirius, an apparent magnitude can also be assigned to man-made objects in Earth orbit. The brightest satellite flares are ranked at −9, and the International Space Station, ISS, the scale is logarithmic, and defined such that each step of one magnitude changes the brightness by a factor of the fifth root of 100, or approximately 2.512. For example, a magnitude 1 star is exactly a hundred times brighter than a magnitude 6 star, the magnitude system dates back roughly 2000 years to the Greek astronomer Hipparchus who classified stars by their apparent brightness, which they saw as size. To the unaided eye, a prominent star such as Sirius or Arcturus appears larger than a less prominent star such as Mizar. For all the other Stars, which are seen by the Help of a Telescope. Note that the brighter the star, the smaller the magnitude, Bright first magnitude stars are 1st-class stars, the system was a simple delineation of stellar brightness into six distinct groups but made no allowance for the variations in brightness within a group. He concluded that first magnitude stars measured 2 arc minutes in apparent diameter, with second through sixth magnitude stars measuring 1 1⁄2′, 1 1⁄12′, 3⁄4′, 1⁄2′, the development of the telescope showed that these large sizes were illusory—stars appeared much smaller through the telescope. However, early telescopes produced a spurious disk-like image of a star that was larger for brighter stars, early photometric measurements demonstrated that first magnitude stars are about 100 times brighter than sixth magnitude stars. Thus in 1856 Norman Pogson of Oxford proposed that a scale of 5√100 ≈2.512 be adopted between magnitudes, so five magnitude steps corresponded precisely to a factor of 100 in brightness. Every interval of one magnitude equates to a variation in brightness of 5√100 or roughly 2.512 times. Consequently, a first magnitude star is about 2.5 times brighter than a second star,2.52 brighter than a third magnitude star,2.53 brighter than a fourth magnitude star. This is the modern system, which measures the brightness, not the apparent size. Using this logarithmic scale, it is possible for a star to be brighter than “first class”, so Arcturus or Vega are magnitude 0, and Sirius is magnitude −1.46. As mentioned above, the scale appears to work in reverse, the larger the negative value, the brighter
25.
Jet Propulsion Laboratory
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The Jet Propulsion Laboratory is a federally funded research and development center and NASA field center in La Cañada Flintridge, California and Pasadena, California, United States. The JPL is managed by the nearby California Institute of Technology for NASA, the laboratorys primary function is the construction and operation of planetary robotic spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASAs Deep Space Network and they are also responsible for managing the JPL Small-Body Database, and provides physical data and lists of publications for all known small Solar System bodies. The JPLs Space Flight Operations Facility and Twenty-Five-Foot Space Simulator are designated National Historic Landmarks, JPL traces its beginnings to 1936 in the Guggenheim Aeronautical Laboratory at the California Institute of Technology when the first set of rocket experiments were carried out in the Arroyo Seco. Malinas thesis advisor was engineer/aerodynamicist Theodore von Kármán, who arranged for U. S. Army financial support for this GALCIT Rocket Project in 1939. In 1941, Malina, Parsons, Forman, Martin Summerfield, in 1943, von Kármán, Malina, Parsons, and Forman established the Aerojet Corporation to manufacture JATO motors. The project took on the name Jet Propulsion Laboratory in November 1943, during JPLs Army years, the laboratory developed two deployed weapon systems, the MGM-5 Corporal and MGM-29 Sergeant intermediate range ballistic missiles. These missiles were the first US ballistic missiles developed at JPL and it also developed a number of other weapons system prototypes, such as the Loki anti-aircraft missile system, and the forerunner of the Aerobee sounding rocket. At various times, it carried out testing at the White Sands Proving Ground, Edwards Air Force Base. A lunar lander was developed in 1938-39 which influenced design of the Apollo Lunar Module in the 1960s. The team lost that proposal to Project Vanguard, and instead embarked on a project to demonstrate ablative re-entry technology using a Jupiter-C rocket. They carried out three successful flights in 1956 and 1957. Using a spare Juno I, the two organizations then launched the United States first satellite, Explorer 1, on February 1,1958, JPL was transferred to NASA in December 1958, becoming the agencys primary planetary spacecraft center. JPL engineers designed and operated Ranger and Surveyor missions to the Moon that prepared the way for Apollo, JPL also led the way in interplanetary exploration with the Mariner missions to Venus, Mars, and Mercury. In 1998, JPL opened the Near-Earth Object Program Office for NASA, as of 2013, it has found 95% of asteroids that are a kilometer or more in diameter that cross Earths orbit. JPL was early to employ women mathematicians, in the 1940s and 1950s, using mechanical calculators, women in an all-female computations group performed trajectory calculations. In 1961, JPL hired Dana Ulery as their first woman engineer to work alongside male engineers as part of the Ranger and Mariner mission tracking teams, when founded, JPLs site was a rocky flood-plain just outside the city limits of Pasadena. Almost all of the 177 acres of the U. S, the city of La Cañada Flintridge, California was incorporated in 1976, well after JPL attained international recognition with a Pasadena address
26.
ArXiv
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In many fields of mathematics and physics, almost all scientific papers are self-archived on the arXiv repository. Begun on August 14,1991, arXiv. org passed the half-million article milestone on October 3,2008, by 2014 the submission rate had grown to more than 8,000 per month. The arXiv was made possible by the low-bandwidth TeX file format, around 1990, Joanne Cohn began emailing physics preprints to colleagues as TeX files, but the number of papers being sent soon filled mailboxes to capacity. Additional modes of access were added, FTP in 1991, Gopher in 1992. The term e-print was quickly adopted to describe the articles and its original domain name was xxx. lanl. gov. Due to LANLs lack of interest in the rapidly expanding technology, in 1999 Ginsparg changed institutions to Cornell University and it is now hosted principally by Cornell, with 8 mirrors around the world. Its existence was one of the factors that led to the current movement in scientific publishing known as open access. Mathematicians and scientists regularly upload their papers to arXiv. org for worldwide access, Ginsparg was awarded a MacArthur Fellowship in 2002 for his establishment of arXiv. The annual budget for arXiv is approximately $826,000 for 2013 to 2017, funded jointly by Cornell University Library, annual donations were envisaged to vary in size between $2,300 to $4,000, based on each institution’s usage. As of 14 January 2014,174 institutions have pledged support for the period 2013–2017 on this basis, in September 2011, Cornell University Library took overall administrative and financial responsibility for arXivs operation and development. Ginsparg was quoted in the Chronicle of Higher Education as saying it was supposed to be a three-hour tour, however, Ginsparg remains on the arXiv Scientific Advisory Board and on the arXiv Physics Advisory Committee. The lists of moderators for many sections of the arXiv are publicly available, additionally, an endorsement system was introduced in 2004 as part of an effort to ensure content that is relevant and of interest to current research in the specified disciplines. Under the system, for categories that use it, an author must be endorsed by an established arXiv author before being allowed to submit papers to those categories. Endorsers are not asked to review the paper for errors, new authors from recognized academic institutions generally receive automatic endorsement, which in practice means that they do not need to deal with the endorsement system at all. However, the endorsement system has attracted criticism for allegedly restricting scientific inquiry, perelman appears content to forgo the traditional peer-reviewed journal process, stating, If anybody is interested in my way of solving the problem, its all there – let them go and read about it. The arXiv generally re-classifies these works, e. g. in General mathematics, papers can be submitted in any of several formats, including LaTeX, and PDF printed from a word processor other than TeX or LaTeX. The submission is rejected by the software if generating the final PDF file fails, if any image file is too large. ArXiv now allows one to store and modify an incomplete submission, the time stamp on the article is set when the submission is finalized
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25 Phocaea
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25 Phocaea is a main-belt asteroid. It was discovered by J. Chacornac at Marseille, on April 6 and it was his first asteroid discovery out of a total of six. It is named after Phocaea, the Greek name of Foça in Turkey, Phocaea has been studied by radar. Photometric observations of this asteroid at the Organ Mesa Observatory in Las Cruces, the brightness near the deepest minimum of the light curve showed changes with phase angle, which is the result of shadows extending across surface irregularities. JPL Ephemeris 2006-Oct-03 Occultation /25 Phocaea at the JPL Small-Body Database Discovery · Orbit diagram · Orbital elements · Physical parameters
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27 Euterpe
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27 Euterpe is a large main-belt asteroid. It was discovered by J. R. Hind on November 8,1853, and named after Euterpē, Euterpe is one of the brightest asteroids in the night sky. On December 25,2015, during an opposition, it will shine with an apparent magnitude of 8.3. Euterpe has been studied by radar, lightcurve plot of 27 Euterpe, Palmer Divide Observatory, B
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Small Solar System body
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A Small Solar System Body is an object in the Solar System that is neither a planet, nor a dwarf planet, nor a natural satellite. The term was first defined in 2006 by the International Astronomical Union, all other objects, except satellites, orbiting the Sun shall be referred to collectively as Small Solar System Bodies. These currently include most of the Solar System asteroids, most Trans-Neptunian Objects, comets and this encompasses all comets and all minor planets other than those that are dwarf planets. Except for the largest, which are in equilibrium, natural satellites differ from small Solar System bodies not in size. The orbits of satellites are not centered on the Sun, but around other Solar System objects such as planets, dwarf planets. Some of the larger small Solar System bodies may be reclassified in future as dwarf planets, the orbits of the vast majority of small Solar System bodies are located in two distinct areas, namely the asteroid belt and the Kuiper belt. These two belts possess some internal structure related to perturbations by the planets, and have fairly loosely defined boundaries. Other areas of the Solar System also encompass small bodies in smaller concentrations and these include the near-Earth asteroids, centaurs, comets, and scattered disc objects
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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
31.
Aten asteroid
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The Aten asteroids are a group of asteroids, whose orbit brings them into proximity with Earth. The group is named after 2062 Aten, the first of its kind, since then, more than 1,000 Atens have been discovered, of which many are classified as potentially hazardous asteroids. For a list of existing articles, see Aten asteroids and List of Aten asteroids, Aten asteroids are defined by having a semi-major axis of less than one astronomical unit, the average distance from the Earth to the Sun. They also have a greater than 0.983 AU. Asteroids orbits can be highly eccentric, an Aten orbit need not be entirely contained within Earths orbit, as nearly all known Aten asteroids have their aphelion greater than 1 AU although their semi-major axis is less than 1 AU. Observation of objects inferior to the Earths orbit is difficult and this difficulty may be the cause of some sampling bias in the apparent preponderance of eccentric Atens, Aten asteroids account for only about 6% of the known near-Earth asteroid population. Many more Apollo-class asteroids are known than Aten-class asteroids, possibly because of the sampling bias, the shortest semi-major axis for any known Aten asteroid is 2008 EY5 at 0.626 AU. A very small possibility of impact remained for 2036, but this was also eliminated, there are also sixteen known Apohele asteroids, traditionally listed as a subclass of Atens, but generally regarded a separate class of their own. Unlike Atens, Apoheles permanently stay within Earths orbit and do not cross it
32.
Asteroid family
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An asteroid family is a population of asteroids that share similar proper orbital elements, such as semimajor axis, eccentricity, and orbital inclination. The members of the families are thought to be fragments of past asteroid collisions, an asteroid family is a more specific term than asteroid group whose members, while sharing some broad orbital characteristics, may be otherwise unrelated to each other. Large prominent families contain several hundred recognized asteroids, small, compact families can have only about ten identified members. About 33% to 35% of asteroids in the belt are family members. There are about 20 to 30 reliably recognized families, with tens of less certain groupings. One family has been identified associated with the dwarf planet Haumea, some studies have tried to find evidence of collisional families among the trojan asteroids, but at present the evidence is inconclusive. The families are thought to form as a result of collisions between asteroids, in many or most cases the parent body was shattered, but there are also several families which resulted from a large cratering event which did not disrupt the parent body. Such cratering families typically consist of a large body and a swarm of asteroids that are much smaller. Some families have complex structures which are not satisfactorily explained at the moment. Due to the method of origin, all the members have closely matching compositions for most families, notable exceptions are those families which formed from a large differentiated parent body. Asteroid families are thought to have lifetimes of the order of a billion years and this is significantly shorter than the Solar Systems age, so few if any are relics of the early Solar System. Such small asteroids then become subject to such as the Yarkovsky effect that can push them towards orbital resonances with Jupiter over time. Once there, they are relatively rapidly ejected from the asteroid belt, tentative age estimates have been obtained for some families, ranging from hundreds of millions of years to less than several million years as for the compact Karin family. Old families are thought to contain few small members, and this is the basis of the age determinations and it is supposed that many very old families have lost all the smaller and medium-sized members, leaving only a few of the largest intact. A suggested example of old family remains are the 9 Metis and 113 Amalthea pair. Further evidence for a number of past families comes from analysis of chemical ratios in iron meteorites. These show that there must have once been at least 50 to 100 parent bodies large enough to be differentiated, when the orbital elements of main belt asteroids are plotted, a number of distinct concentrations are seen against the rather uniform background distribution of generic asteroids. These concentrations are the asteroid families, the proper elements are related constants of motion that remain almost constant for times of at least tens of millions of years, and perhaps longer
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Jupiter trojan
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The Jupiter trojans, commonly called Trojan asteroids or just Trojans, are a large group of asteroids that share the orbit of the planet Jupiter around the Sun. Relative to Jupiter, each Trojan librates around one of Jupiters two stable Lagrangian points, L4, lying 60° ahead of the planet in its orbit, and L5, 60° behind. Jupiter trojans are distributed in two elongated, curved regions around these Lagrangian points with an average axis of about 5.2 AU. The first Jupiter trojan discovered,588 Achilles, was spotted in 1906 by German astronomer Max Wolf, a total of 6,178 Jupiter trojans have been found as of January 2015. By convention they are named after a mythological figure from the Trojan War. The total number of Jupiter trojans larger than 1 km in diameter is believed to be about 1 million, like main-belt asteroids, Jupiter trojans form families. Jupiter trojans are bodies with reddish, featureless spectra. The Jupiter trojans densities vary from 0.8 to 2.5 g·cm−3, Jupiter trojans are thought to have been captured into their orbits during the early stages of the Solar Systems formation or slightly later, during the migration of giant planets. NASA has announced the discovery of an Earth trojan, the trapped body will librate slowly around the point of equilibrium in a tadpole or horseshoe orbit. These leading and trailing points are called the L4 and L5 Lagrange points, however, no asteroids trapped in Lagrange points were observed until more than a century after Lagranges hypothesis. Those associated with Jupiter were the first to be discovered, E. E. Barnard made the first recorded observation of a Trojan,1999 RM11, in 1904, but neither he nor others appreciated its significance at the time. Barnard believed he saw the recently discovered Saturnian satellite Phoebe, which was only two away in the sky at the time, or possibly an asteroid. The objects identity was not realized until its orbit was calculated in 1999, in 1906–1907 two more Jupiter trojans were found by fellow German astronomer August Kopff. Hektor, like Achilles, belonged to the L4 swarm, whereas Patroclus was the first asteroid known to reside at the L5 Lagrangian point, by 1938,11 Jupiter trojans had been detected. This number increased to 14 only in 1961, as instruments improved, the rate of discovery grew rapidly, by January 2000, a total of 257 had been discovered, by May 2003, the number had grown to 1,600. Asteroids in the L4 group are named after Greek heroes, confusingly,617 Patroclus was named before the Greece/Troy rule was devised, and a Greek name thus appears in the Trojan node. The Greek node also has one misplaced asteroid,624 Hektor, estimates of the total number of Jupiter trojans are based on deep surveys of limited areas of the sky. The L4 swarm is believed to hold between 160–240,000 asteroids with diameters larger than 2 km and about 600,000 with diameters larger than 1 km
, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
