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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. 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)''. 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. Most of the Kirkwood gaps are depleted, unlike the mean-motion resonanc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kirkwood Gaps
A Kirkwood gap is a gap or dip in the distribution of the semi-major axis, semi-major axes (or equivalently of the orbital periods) of the orbits of asteroid belt, main-belt asteroids. They correspond to the locations of orbital resonances with Jupiter. For example, there are very few asteroids with semimajor axis near 2.50 Astronomical unit, 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)''. 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 Washington & Jefferson College, Jefferson College in Canonsburg, Pennsylvan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eccentricity (orbit)
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: ''e'' = 0 * elliptic orbit: 0 < ''e'' < 1 * |
University Of Pittsburgh Press
The University of Pittsburgh Press is a scholarly publishing house and a major American university press, part of the University of Pittsburgh. The university and the press are located in Pittsburgh, Pennsylvania, in the United States. The press publishes several series in the humanities and social sciences, including Illuminations—Cultural Formations of the Americas; Pitt Latin American Series; Pitt Series in Russian and East European Studies, Pittsburgh Series in Composition, Literary, and Culture; Pittsburgh/Konstanz Series in Philosophy and History of Science; Culture, Politics, and the Built Environment; Central Eurasia in Context, and Latinx and Latin American Profiles. The press is especially known for literary publishing, particularly its Pitt Poetry Series, the Agnes Lynch Starrett Poetry Prize, and the Drue Heinz Literature Prize. The press also publishes the winner of the annual Donald Hall Prize, awarded by the Association of Writers & Writing Programs and the winn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cybele Group
The Cybele asteroids (also known as the "Cybeles") are a dynamical group of asteroids, named after the asteroid 65 Cybele. Considered by some as the last outpost of an extended asteroid belt, the group consists of just over 2000 members and a few collisional families. The Cybeles are in a 7:4 orbital resonance with Jupiter. Their orbit is defined by an osculating semi-major axis of 3.28 to 3.70 AU, with an eccentricity of less than 0.3, and an inclination less than 25°. The dynamical Cybele group is located adjacent to the outermost asteroid belt, beyond the Hecuba gap – the 2:1 resonant zone with Jupiter, where the Griqua asteroids are located – and inside the orbital region of the Hilda asteroids (3:2 resonance), which are themselves followed by the Jupiter trojans (1:1 resonance) further out. Description Three known asteroid families exist within the Cybele group: the Sylvia family ( 603), the Huberta family and the Ulla family (903). A potential fou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbital Resonance
In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly, this relationship is found between a pair of objects (binary resonance). The physical principle behind orbital resonance is similar in concept to pushing a child on a swing, whereby the orbit and the swing both have a natural frequency, and the body doing the "pushing" will act in periodic repetition to have a cumulative effect on the motion. Orbital resonances greatly enhance the mutual gravitational influence of the bodies (i.e., their ability to alter or constrain each other's orbits). In most cases, this results in an ''unstable'' interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists. Under some circumstances, a resonant system can be self-correcting and thus stable. Examples are the 1:2:4 resonance o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
87 Sylvia
Sylvia (minor planet designation: 87 Sylvia) is the one of the largest asteroids (approximately tied for 7th place, to within measurement uncertainties). It is the parent body of the Sylvia family and member of Cybele group located beyond the main asteroid belt (see minor-planet groups). Sylvia was the first asteroid known to possess more than one moon. Discovery and naming Sylvia was discovered by N. R. Pogson on May 16, 1866, from Madras (Chennai), India.Pogson, N. R. (1866), Minor Planet (87) Sylvia', Monthly Notices of the Royal Astronomical Society, Vol. 26, p. 311 (June 1866) Antonio Paluzie-Borrell, writing in Paul Herget's ''The Names of the Minor Planets'' (1955), mistakenly states that the name honors Sylvie Petiaux-Hugo Flammarion, the first wife of astronomer Camille Flammarion. In fact, in the article announcing the discovery of the asteroid, Pogson explained that he selected the name in reference to Rhea Silvia, mother of Romulus and Remus (''MNRAS'', 1866). Ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
10 Hygiea
Hygiea (minor-planet designation: 10 Hygiea) is a major asteroid and possible dwarf planet located in the main asteroid belt. With a diameter of and a mass estimated to be 3% of the total mass of the belt, it is the fourth-largest asteroid in the Solar System by both volume and mass. In some spectral classifications it is the largest of the dark C-type asteroids with a carbonaceous surface, whereas in others it is second after 1 Ceres. Observations taken with the Very Large Telescope's SPHERE imager in 2017 and 2018, and announced in late 2019, revealed that Hygiea is nearly spherical and is close to a hydrostatic equilibrium shape. The authors of the study therefore consider it a possible dwarf planet. However, Hygiea is conjectured to have been disrupted by an impact, with the subsequent debris reaccumulating, rather than being massive enough to be plastic. The disruptive impact produced the largest known collisional family. Observation Despite its size, Hygiea appears v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2 Pallas
Pallas ( minor-planet designation: 2 Pallas) is the second asteroid to have been discovered, after Ceres. It is believed to have a mineral composition similar to carbonaceous chondrite meteorites, like Ceres, though significantly less hydrated than Ceres. It is the third-largest asteroid in the Solar System by both volume and mass, and is a likely remnant protoplanet. It is 79% the mass of Vesta and 22% the mass of Ceres, constituting an estimated 7% of the mass of the asteroid belt. Its estimated volume is equivalent to a sphere in diameter, 90–95% the volume of Vesta. During the planetary formation era of the Solar System, objects grew in size through an accretion process to approximately the size of Pallas. Most of these protoplanets were incorporated into the growth of larger bodies, which became the planets, whereas others were ejected by the planets or destroyed in collisions with each other. Pallas, Vesta and Ceres appear to be the only intact bodies from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1 Ceres
Ceres (; minor-planet designation: 1 Ceres) is a dwarf planet in the asteroid belt between the orbits of Mars and Jupiter. It was the first asteroid discovered, on 1 January 1801, by Giuseppe Piazzi at Palermo Astronomical Observatory in Sicily and announced as a new planet. Ceres was later classified as an asteroid and then a dwarf planetthe only one always inside Neptune's orbit. Ceres's small size means that even at its brightest, it is too dim to be seen by the naked eye, except under extremely dark skies. Its apparent magnitude ranges from 6.7 to 9.3, peaking at opposition (when it is closest to Earth) once every 15- to 16-month synodic period. As a result, its surface features are barely visible even with the most powerful telescopes, and little was known about it until the robotic NASA spacecraft ''Dawn'' approached Ceres for its orbital mission in 2015. ''Dawn'' found Ceres's surface to be a mixture of water ice, and hydrated minerals such as carbonates and clay. Gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
4 Vesta
Vesta ( minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt, with a mean diameter of . It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta, the virgin goddess of home and hearth from Roman mythology. Vesta is thought to be the second-largest asteroid, both by mass and by volume, after the dwarf planet Ceres, though in volume it overlaps with the uncertainty in the measurements of 2 Pallas.Marsset, M., Brož, M., Vernazza, P. et al. The violent collisional history of aqueously evolved (2) Pallas. Nat Astron 4, 569–576 (2020). https://doi.org/10.1038/s41550-019-1007-5 Measurements give it a nominal volume only slightly larger than that of Pallas (about 5% greater, which is the magnitude of the uncertainties in measurement), but it is 25% to 30% more massive. It constitutes an estimated 9% of the mass of the asteroid belt. Vesta is the only known remaining rocky protoplanet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cybele Asteroids
The Cybele asteroids (also known as the "Cybeles") are a dynamical group of asteroids, named after the asteroid 65 Cybele. Considered by some as the last outpost of an extended asteroid belt, the group consists of just over 2000 members and a few collisional families. The Cybeles are in a 7:4 orbital resonance with Jupiter. Their orbit is defined by an osculating semi-major axis of 3.28 to 3.70 AU, with an eccentricity of less than 0.3, and an inclination less than 25°. The dynamical Cybele group is located adjacent to the outermost asteroid belt, beyond the Hecuba gap – the 2:1 resonant zone with Jupiter, where the Griqua asteroids are located – and inside the orbital region of the Hilda asteroids (3:2 resonance), which are themselves followed by the Jupiter trojans (1:1 resonance) further out. Description Three known asteroid families exist within the Cybele group: the Sylvia family ( 603), the Huberta family and the Ulla family ( 903). A potential f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
279 Thule
Thule, minor planet designation: 279 Thule, is a large asteroid from the outer asteroid belt. It is classified as a D-type asteroid and is probably composed of organic-rich silicates, carbon and anhydrous silicates. Thule was the first asteroid discovered with a semi-major axis greater than 4 AU. It was discovered by Johann Palisa on 25 October 1888 in Vienna and was named after the ultimate northern land of Thule. Thule asteroids Thule was the first discovered member of the ''Thule dynamical group'', which as of 2008 is known to consist of three objects: 279 Thule, , and . The orbits of these bodies are unusual. They orbit in the outermost edge of the asteroid belt in a 4:3 orbital resonance with Jupiter, the result of the periodic force Jupiter exerts on a body with Thule's orbital period, in the same way (though with the reverse effect) as the Kirkwood gaps in the more inner parts of the asteroid belt. References External links * * Thule asteroids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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