"no repeated looping: each one traces a full horseshoe with respect to the other). The following explanation relates to an asteroid which is in such an orbit around the Sun, and is also affected by the Earth. The asteroid is in almost the same solar orbit as Earth. Both take approximately one year to orbit the Sun. It is also necessary to grasp two rules of orbit dynamics: The horseshoe orbit arises because the gravitational attraction of the Earth changes the shape of the elliptical orbit of the asteroid. The shape changes are very small but result in significant changes"
"Solar System The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, such as the five dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the moons—two are larger than the smallest planet, Mercury. The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system's mass is in the Sun, with"
"imagery, and sorted by volume. Some omitted objects are larger than the ones included here, notably Eris, because these have not been imaged in high quality. Solar System The Solar System is the gravitationally bound system of the Sun and the objects that orbit it, either directly or indirectly. Of the objects that orbit the Sun directly, the largest are the eight planets, with the remainder being smaller objects, such as the five dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly—the moons—two are larger than the smallest planet, Mercury. The Solar System formed"
"other bodies orbiting the Sun. The principal component of the Solar System is the Sun, a G2 main-sequence star that contains 99.86% of the system's known mass and dominates it gravitationally. The Sun's four largest orbiting bodies, the giant planets, account for 99% of the remaining mass, with Jupiter and Saturn together comprising more than 90%. The remaining objects of the Solar System (including the four terrestrial planets, the dwarf planets, moons, asteroids, and comets) together comprise less than 0.002% of the Solar System's total mass. Most large objects in orbit around the Sun lie near the plane of Earth's"
"Small Solar System body A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first defined in 2006 by the International Astronomical Union (IAU) as follows: ""All other objects, except satellites, orbiting the Sun shall be referred to collectively as 'Small Solar System Bodies' "". This encompasses all comets and all minor planets other than those that are dwarf planets. Thus SSSBs are: the classical asteroids, with the exception of the dwarf planet Ceres; the trojans; and the centaurs and trans-Neptunian objects,"
"possess some internal structure related to perturbations by the major planets (particularly Jupiter and Neptune, respectively), and have fairly loosely defined boundaries. Other areas of the Solar System also encompass small bodies in smaller concentrations. These include the near-Earth asteroids, centaurs, comets, and scattered disc objects. Small Solar System body A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite. The term was first defined in 2006 by the International Astronomical Union (IAU) as follows: ""All other objects, except satellites, orbiting the Sun shall be"
"Minor planet A minor planet is an astronomical object in direct orbit around the Sun (or more broadly, any star with a planetary system) that is neither a planet nor exclusively classified as a comet. Before 2006 the International Astronomical Union (IAU) officially used the term ""minor planet"", but during that year's meeting it reclassified minor planets and comets into dwarf planets and small Solar System bodies (SSSBs). Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, and other trans-Neptunian objects. As of 2018, the orbits of 757,626 minor planets were archived at the Minor Planet Center,"
"from smaller rocky planets like Mars to gas giants like Jupiter. Any natural Sun-orbiting body that has not reached hydrostatic equilibrium is classified by the IAU as a small Solar System body (SSB). These come in many non-spherical shapes which are lumpy masses accreted haphazardly by in-falling dust and rock; not enough mass falls in to generate the heat needed to complete the rounding. Some SSSBs are just collections of relatively small rocks that are weakly held next to each other by gravity but are not actually fused into a single big bedrock. Some larger SSSBs are nearly round but"
"the smallest natural satellites. Known satellite systems of the Solar System consisting of multiple objects or around planetary mass objects, in order of perihelion: Natural satellite systems, particularly those involving multiple planetary mass objects can have complex interactions which can have effects on multiple bodies or across the wider system. Ring systems are collections of dust, moonlets, or other small objects. The most notable examples are those around Saturn, but the other three gas giants (Jupiter, Uranus and Neptune) also have ring systems. Studies of exoplanets indicate that they may be common around giant planets. The 90 million km (0.6"
"unmapped. There are also ongoing studies of the region between Mercury and the Sun. Objects may yet be discovered in the Solar System's uncharted regions. Currently, the furthest known objects, such as Comet West, have aphelia around 70,000 AU from the Sun, but as the Oort cloud becomes better known, this may change. The Solar System is located in the Milky Way, a barred spiral galaxy with a diameter of about 100,000 light-years containing about 100 billion stars. The Sun resides in one of the Milky Way's outer spiral arms, known as the Orion–Cygnus Arm or Local Spur. The Sun"
"93% of all discovered and numbered minor planets within the Solar System. The JPL Small-Body Database lists over 670,000 known main belt asteroids. The semi-major axis of an asteroid is used to describe the dimensions of its orbit around the Sun, and its value determines the minor planet's orbital period. In 1866, Daniel Kirkwood announced the discovery of gaps in the distances of these bodies' orbits from the Sun. They were located in positions where their period of revolution about the Sun was an integer fraction of Jupiter's orbital period. Kirkwood proposed that the gravitational perturbations of the planet led"
"thousand minor planets. ""Prometheus"" orbits the Sun in the outer main-belt at a distance of 2.6–3.2 AU once every 5.00 years (1,827 days). Its orbit has an eccentricity of 0.10 and an inclination of 3° with respect to the ecliptic. According to the surveys carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, ""Prometheus"" measures 14.2 kilometers in diameter, and its surface has an albedo of 0.126. As of 2017, its spectral type, rotation period and shape remain unknown. This minor planet was named for Prometheus, a Titan from Greek mythology, who stole the fire from"
"Ultraviolet light is strongly attenuated by Earth's ozone layer, so that the amount of UV varies greatly with latitude and has been partially responsible for many biological adaptations, including variations in human skin color in different regions of the Earth. The Sun has eight known planets. This includes four terrestrial planets (Mercury, Venus, Earth, and Mars), two gas giants (Jupiter and Saturn), and two ice giants (Uranus and Neptune). The Solar System also has at least five dwarf planets, an asteroid belt, numerous comets, and a large number of icy bodies which lie beyond the orbit of Neptune. Sun The"
"course of its year. A body's closest approach to the Sun is called its ""perihelion"", whereas its most distant point from the Sun is called its ""aphelion"". The orbits of the planets are nearly circular, but many comets, asteroids, and Kuiper belt objects follow highly elliptical orbits. The positions of the bodies in the Solar System can be predicted using numerical models. Although the Sun dominates the system by mass, it accounts for only about 2% of the angular momentum. The planets, dominated by Jupiter, account for most of the rest of the angular momentum due to the combination of"
"the small body being scattered and the degree to which it must be scattered. In the domain of the solar planetary disc, there is little variation in the average values of ""k"" for small bodies at a particular distance from the Sun. If Λ > 1, then the body will likely clear out the small bodies in its orbital zone. Stern and Levison used this discriminant to separate the gravitionally rounded, Sun-orbiting bodies into ""überplanets"", which are ""dynamically important enough to have cleared its neighboring planetesimals"", and ""unterplanets"". The überplanets are the eight most massive solar orbiters (i.e. the IAU"
"near the Solar System. Trans-Neptunian object A trans-Neptunian object (TNO, also written transneptunian object) is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has a semi-major axis of 30.1 astronomical units (AU). Typically, TNOs are further divided into the classical and resonant objects of the Kuiper belt, the scattered disc and detached objects with the sednoids being the most distant ones. As of October 2018, the catalog of minor planets contains 528 numbered and more than 2,000 unnumbered TNOs. The first trans-Neptunian object to be discovered was Pluto in"
"moons. The centaurs and many short-period comets also orbit in this region. Due to their greater distance from the Sun, the solid objects in the outer Solar System contain a higher proportion of volatiles, such as water, ammonia, and methane than those of the inner Solar System because the lower temperatures allow these compounds to remain solid. The four outer planets, or giant planets (sometimes called Jovian planets), collectively make up 99% of the mass known to orbit the Sun. Jupiter and Saturn are together more than 400 times the mass of Earth and consist overwhelmingly of hydrogen and helium."
"Centaur (minor planet) Centaurs are small Solar System bodies with a semi-major axis between those of the outer planets. They generally have unstable orbits because they cross or have crossed the orbits of one or more of the giant planets; almost all their orbits have dynamic lifetimes of only a few million years, but there is one centaur, , which may be in a stable (though retrograde) orbit. Centaurs typically behave with characteristics of both asteroids and comets. They are named after the mythological centaurs that were a mixture of horse and human. It has been estimated that there are"
"orbit, known as the ecliptic. The planets are very close to the ecliptic, whereas comets and Kuiper belt objects are frequently at significantly greater angles to it. All the planets, and most other objects, orbit the Sun in the same direction that the Sun is rotating (counter-clockwise, as viewed from above Earth's north pole). There are exceptions, such as Halley's Comet. The overall structure of the charted regions of the Solar System consists of the Sun, four relatively small inner planets surrounded by a belt of mostly rocky asteroids, and four giant planets surrounded by the Kuiper belt of mostly"
"Properties of Near Earth Asteroids. Most detailed information is available from and . Minor planet A minor planet is an astronomical object in direct orbit around the Sun (or more broadly, any star with a planetary system) that is neither a planet nor exclusively classified as a comet. Before 2006 the International Astronomical Union (IAU) officially used the term ""minor planet"", but during that year's meeting it reclassified minor planets and comets into dwarf planets and small Solar System bodies (SSSBs). Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, and other trans-Neptunian objects. As of 2018,"
"natural satellites (moons) differ from small Solar System bodies not in size, but in their orbits. The orbits of natural satellites are not centered on the Sun, but around other Solar System objects such as planets, dwarf planets, and small Solar System bodies. Some of the larger small Solar System bodies may be reclassified in future as dwarf planets, pending further examination to determine whether or not they are in hydrostatic equilibrium. 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"
"Discovery and exploration of the Solar System Discovery and exploration of the Solar System is observation, visitation, and increase in knowledge and understanding of Earth's ""cosmic neighborhood"". This includes the Sun, Earth and the Moon, the major planets including Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune, their satellites, as well as smaller bodies including comets, asteroids, and dust. For many thousands of years, astronomers maintained a geocentric world view and did not recognize the existence of a Solar System. Most believed Earth was stationary at the center of the Universe and categorically different from the divine or ethereal objects"
"Earth-crossing asteroids. They are the largest group of near-Earth objects with approximately 10 thousand known members. As it just grazes the orbit of Earth, the Minor Planet Center (MPC), groups it to the non-Earth crossing Amor asteroids. It orbits the Sun at a distance of 1.015–3.3 AU once every 3 years and 1 month (1,140 days; semi-major axis of 2.14 AU). Its orbit has an eccentricity of 0.52 and an inclination of 12° with respect to the ecliptic. The body's observation arc begins with a precovery taken at the Siding Spring Observatory on in July 1981, more than 18 years"
"they produce small fragments that occasionally fall on Earth. These rocks are called meteorites and provide information about the primordial solar nebula. Most of these fragments have the size of sand grains. They burn up in the Earth's atmosphere, causing them to glow like meteors. A comet is a small Solar System body that orbits the Sun and (at least occasionally) exhibits a coma (or atmosphere) and/or a tail—both primarily from the effects of solar radiation upon the comet's nucleus, which itself is a minor body composed of rock, dust, and ice. The Kuiper belt, sometimes called the Edgeworth–Kuiper belt,"
"zone of the Solar System"", enclosing the inner and the outer Solar System. The Kuiper belt is a great ring of debris similar to the asteroid belt, but consisting mainly of objects composed primarily of ice. It extends between 30 and 50 AU from the Sun. Though it is estimated to contain anything from dozens to thousands of dwarf planets, it is composed mainly of small Solar System bodies. Many of the larger Kuiper belt objects, such as Quaoar, Varuna, and Orcus, may prove to be dwarf planets with further data. There are estimated to be over 100,000 Kuiper belt"
"also has hydrocarbon lakes. Four of the largest natural satellites, Europa, Ganymede, Callisto, and Titan, are thought to have subsurface oceans of liquid water, while smaller Enceladus may have localized subsurface liquid water. Of the objects within our Solar System known to have natural satellites, there are 76 in the asteroid belt (five with two each), four Jupiter trojans, 39 near-Earth objects (two with two satellites each), and 14 Mars-crossers. There are also 84 known natural satellites of trans-Neptunian objects. Some 150 additional small bodies have been observed within the rings of Saturn, but only a few were tracked long"
"the LINEAR system alone has discovered 138,393 asteroids. Among all the surveys, 4711 near-Earth asteroids have been discovered including over 600 more than in diameter. Traditionally, small bodies orbiting the Sun were classified as comets, asteroids, or meteoroids, with anything smaller than one meter across being called a meteoroid. Beech and Steel's 1995 paper proposed a meteoroid definition including size limits. The term ""asteroid"", from the Greek word for ""star-like"", never had a formal definition, with the broader term minor planet being preferred by the International Astronomical Union. However, following the discovery of asteroids below ten meters in size, Rubin"
"Since the dawn of the Space Age, close observation by space probes has found that Earth and the other planets share characteristics such as volcanism, hurricanes, tectonics, and even hydrology. Planets are generally divided into two main types: large low-density giant planets, and smaller rocky terrestrials. There are eight planets in the Solar System. In order of increasing distance from the Sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four giant planets, Jupiter, Saturn, Uranus, and Neptune. Six of the planets are orbited by one or more natural satellites. Several thousands of planets around other"
"asteroids. A minor planet seen releasing gas may be dually classified as a comet. Objects are called dwarf planets if their self-gravity is sufficient to achieve hydrostatic equilibrium and form an ellipsoidal shape. All other minor planets and comets are called ""small Solar System bodies"". The IAU stated that the term ""minor planet"" may still be used, but the term ""small Solar System body"" will be preferred. However, for purposes of numbering and naming, the traditional distinction between minor planet and comet is still used. Hundreds of thousands of minor planets have been discovered within the Solar System and thousands"
"580 Selene Selene (minor planet designation: 580 Selene) is a minor planet orbiting the Sun in the asteroid belt. The name Selene is that of an ancient Greek goddess of the Moon. This body orbits the Sun nearly midway between the orbits of Mars and Jupiter. The orbital eccentricity is slightly lower than that of Mars. Based on its light curve, Selene has an estimated rotation period of 0.3947±0.0004 days, or just under 9.5 hours. During each rotation, the apparent magnitude varies by 0.27. The approximate diameter of this asteroid is 46 km. (Some sources list a diameter of up"
"is the small moon Enceladus, which ejects as much as 1,000 kg/s of water vapor from the geysers on its south pole, a portion of which is ionized and forced to co-rotate with the Saturn’s magnetic field. This loads the field with as much as 100 kg of water group ions per second. This plasma gradually moves out from the inner magnetosphere via the interchange instability mechanism and then escapes through the magnetotail. The interaction between Saturn's magnetosphere and the solar wind generates bright oval aurorae around the planet's poles observed in visible, infrared and ultraviolet light. The aurorae are"
"orbital eccentricity. There are several thousand known trojan minor planets orbiting the Sun. Most of these orbit near Jupiter's Lagrangian points, the traditional Jupiter trojans. there are also 13 Neptune trojans, 7 Mars trojans, 2 Uranus trojans ( and 2014 YX49) and 1 Earth trojan () known to exist. The Saturnian system contains two sets of trojan moons. Both Tethys and Dione have two trojan moons, Telesto and Calypso in Tethys's and respectively, and Helene and Polydeuces in Dione's and respectively. Polydeuces is noticeable for its wide libration: it wanders as far as ±30° from its Lagrangian point and ±2%"
"km. The first centaur discovered, 2060 Chiron, has also been classified as comet (95P) because it develops a coma just as comets do when they approach the Sun. Comets are small Solar System bodies, typically only a few kilometres across, composed largely of volatile ices. They have highly eccentric orbits, generally a perihelion within the orbits of the inner planets and an aphelion far beyond Pluto. When a comet enters the inner Solar System, its proximity to the Sun causes its icy surface to sublimate and ionise, creating a coma: a long tail of gas and dust often visible to"