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4450 Pan
4450 Pan ('' prov. designation:'' ) is a highly eccentric asteroid and contact binary, classified as a potentially hazardous asteroid and near-Earth object of the Apollo group, approximately 1.1 kilometers in diameter. It was discovered on 25 September 1987, by American astronomers Eugene and Carolyn Shoemaker at Palomar Observatory in California, United States. It was named after Pan from Greek mythology. Naming This minor planet was named after Pan, the Greek god of nature, shepherds of flocks and wild animals. In art, he was represented as a horned half-man, half goat. Pan was worshiped by the citizens of Athens, after he had inspired panic in the hearts of their Persians enemies in the Battle of Marathon ''(also see 4356 Marathon)''. The modern word "panic" origins from this myth. The name ''Pan'' has also been given to Saturn XVIII, one of the moons of Saturn. The official naming citation was published by the Minor Planet Center on 30 January 1991 (). Orbit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carolyn Shoemaker
Carolyn Jean Spellmann Shoemaker (June 24, 1929 – August 13, 2021) was an American astronomer and a co-discoverer of Comet Shoemaker–Levy 9, Comet Shoemaker–Levy 9. She discovered 32 comets (then a record for the most by an individual) and more than 500 asteroids. Having earned degrees in history, political science, and English literature, she had little interest in planetary science until she met and married geologist Eugene Merle Shoemaker. Her career in astronomy began when she demonstrated good stereopsis, stereoscopic vision, a particularly valuable quality for looking for objects in near-Earth space. Despite the fact that her degrees were not in science, having that visual ability motivated the California Institute of Technology (Caltech) to hire her as a research assistant on a team led by her husband. She went on to making record-setting discoveries in the field of astronomy, as well as being awarded honorary degrees and many professional awards. Personal l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contact Binary (small Solar System Body)
A contact binary is a small Solar System body, such as a minor planet or comet, that is composed of two bodies that have gravitated toward each other until they touch, resulting in a bilobated, peanut-like overall shape. Contact binaries are distinct from true binary systems such as binary asteroids where both components are separated. The term is also used for stellar contact binaries. An example of a contact binary is the Kuiper belt object 486958 Arrokoth, which was imaged by the ''New Horizons'' spacecraft during its flyby in January 2019. History The existence of contact binary asteroids was first speculated by planetary scientist Allan F. Cook in 1971, who sought for potential explanations for the extremely elongated shape of the Jupiter trojan asteroid 624 Hektor, whose longest axis measures roughly across and is twice as long as its shorter axes according to light curve measurements. Astronomers William K. Hartmann and Dale P. Cruikshank performed further invest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Inclination
Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference 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 satellite's orbit is the same as the Earth's equatorial plane, and the satellite's orbital inclination is 0°. The general case for a circular orbit is that it is tilted, spending half an orbit over the northern hemisphere and half over the southern. If the orbit swung between 20° north latitude and 20° south latitude, then its orbital inclination would be 20°. Orbits The inclination is one of the six orbital elements describing the shape and orientation of a celestial orbit. It is the angle between the orbital 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 planet's equator. For pla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Eccentricity
In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit (or capture orbit), and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is normally used for the isolated two-body problem, but extensions exist for objects following a rosette orbit through the Galaxy. Definition 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 eccentricity may take the following values: * Circular orbit: * Elliptic orbit: * Parabolic trajectory: * Hyperbolic trajectory: The eccentricity is given by e = \sqrt where ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kirkwood Gap
A Kirkwood gap is a gap or dip in the distribution of the semi-major axes (or equivalently of the orbital periods) of the orbits of main-belt asteroids. They correspond to the locations of orbital resonances with Jupiter. The gaps were first noticed in 1866 by Daniel Kirkwood, who also correctly explained their origin in the orbital resonances with Jupiter while a professor at Jefferson College in Canonsburg, Pennsylvania. For example, there are very few asteroids with semimajor axis near 2.50 AU, period 3.95 years, which would make three orbits for each orbit of Jupiter (hence, called the 3:1 orbital resonance). Other orbital resonances correspond to orbital periods whose lengths are simple fractions of Jupiter's. The weaker resonances lead only to a depletion of asteroids, while spikes in the histogram are often due to the presence of a prominent asteroid family ''(see List of asteroid families)''. Most of the Kirkwood gaps are depleted, unlike the mean-motion resonance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minor Planet Circulars
The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function The Minor Planet Center is the official worldwide organization in charge of collecting observational data for minor planets (such as asteroids), calculating their orbits and publishing this information via the '' Minor Planet Circulars''. Under the auspices of the International Astronomical Union (IAU), it operates at the Smithsonian Astrophysical Observatory, which is part of the Center for Astrophysics along with the Harvard College Observatory. The MPC runs a number of free online services for observers to assist them in observing minor planets and comets. The complete catalogue of minor planet orbits (sometimes referred to as the "Minor Planet Catalogue") may also be freely downloaded. In addition to astrometric data, the MPC coll ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minor Planet Center
The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function The Minor Planet Center is the official worldwide organization in charge of collecting observational data for minor planets (such as asteroids), calculating their orbits and publishing this information via the '' Minor Planet Circulars''. Under the auspices of the International Astronomical Union (IAU), it operates at the Smithsonian Astrophysical Observatory, which is part of the Center for Astrophysics along with the Harvard College Observatory. The MPC runs a number of free online services for observers to assist them in observing minor planets and comets. The complete catalogue of minor planet orbits (sometimes referred to as the "Minor Planet Catalogue") may also be freely downloaded. In addition to astrometric data, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moons Of Saturn
The moons of Saturn are numerous and diverse, ranging from tiny moonlets only tens of meters across to the enormous Titan (moon), Titan, which is larger than the planet Mercury (planet), Mercury. There are 274 natural satellite, moons with confirmed orbits, the most of any planet in the Solar System. This number does not include the many thousands of moonlets embedded within Rings of Saturn, Saturn's dense rings, nor hundreds of possible kilometer-sized distant moons that have been observed on single occasions. Three moons are particularly notable. Titan is the second-List of natural satellites, largest moon in the Solar System (after Jupiter's Ganymede (moon), Ganymede), with a Atmosphere of Titan#Composition, nitrogen-rich Earth-like Atmosphere of Titan, atmosphere and a landscape featuring river networks and lakes of Titan, hydrocarbon lakes. Enceladus emits jets of ice from its south-polar region and is covered in a deep layer of snow. Iapetus (moon), Iapetus has contrasting ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saturn XVIII
Pan is the innermost named moon of Saturn. It is approximately 35 kilometres across and 23 km wide and orbits within the Encke Gap in Saturn's A Ring. Pan is a ring shepherd and is responsible for keeping the Encke Gap free of ring particles. It is sometimes described as having the appearance of a walnut, or ravioli. Pan was discovered by Mark R. Showalter in 1990 from analysis of old ''Voyager 2'' probe photos and received the provisional designation because the discovery images dated back to 1981.IAUC 5052: ''Saturn'' July 16, 1990 (discovery) Prediction and discovery The existence of a moon in the Encke Gap was first predicted by Jeffrey N. Cuzzi and Jeffrey D. Scargle in 1985, based on wavy edges of the gap which indicated a gravitational disturbance. In 1986, Showalter ''et al.'' ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Battle Of Marathon
The Battle of Marathon took place in 490 BC during the first Persian invasion of Greece. It was fought between the citizens of Athens (polis), Athens, aided by Plataea, and a Achaemenid Empire, Persian force commanded by Datis and Artaphernes (nephew of Darius I), Artaphernes. The battle was the culmination of the first attempt by Persia under King Darius I of Persia, Darius I to subjugate Ancient Greece, Greece. The Greek army inflicted a crushing defeat on the more numerous Persians, marking a turning point in the Greco-Persian Wars. The first Persian invasion was a response to Athenian involvement in the Ionian Revolt, when Athens and Eretria sent a force to support the cities of Ionia in their attempt to overthrow Persian rule. The Athenians and Eretrians had succeeded in capturing and burning Sardis, but they were then forced to retreat with heavy losses. In response to this raid, Darius swore to burn down Athens and Eretria. According to Herodotus, Darius had his bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Minor Planet
According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor planet'', but that year's meeting IAU definition of planet, reclassified minor planets and comets into dwarf planets and Small Solar System body, small Solar System bodies (SSSBs).Press release, IAU 2006 General Assembly: Result of the IAU Resolution votes International Astronomical Union, August 24, 2006. Accessed May 5, 2008. In contrast to the eight official planets of the Solar System, all minor planets fail to clearing the neighborhood, clear their orbital neighborhood. Minor planets include asteroids (near- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
