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Minor Planets
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 reclassified minor planets and comets into dwarf planets and 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. Minor planets include s ( |
Trans-Neptunian Objects
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 2020, the catalog of minor planets contains 678 numbered and more than 2,000 unnumbered TNOs. The first trans-Neptunian object to be discovered was Pluto in 1930. It took until 1992 to discover a second trans-Neptunian object orbiting the Sun directly, 15760 Albion. The most massive TNO known is Eris, followed by Pluto, , , and . More than 80 satellites have been discovered in orbit of trans-Neptunian objects. TNOs vary in color and are either grey-blue (BB) or very red (RR). They are thought to be composed of mixtures of rock, amorphous car ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroid
An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. Of the roughly one million known asteroids the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 AU from the Sun, in the main asteroid belt. Asteroids are generally classified to be of three types: C-type, M-type, and S-type. These were named after and are generally identified with carbonaceous, metallic, and silicaceous compositions, respectively. The size of asteroids varies greatly; the largest, Ceres, is almost across and qualifies as a dwarf planet. The total mass of all the asteroids combined is only 3% that of Earth's Moon. The majority of main belt asteroids follow slightly elliptical, stable orbits, revolving in the same direction as the Earth and taking from three to six years to co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
594913 ꞌAylóꞌchaxnim
594913 ꞌAylóꞌchaxnim (provisional designation ) is a large near-Earth asteroid discovered by the Zwicky Transient Facility on 4 January 2020. It is the first asteroid discovered to have an orbit completely within Venus's orbit, and is thus the first and only known member of the eponymous ꞌAylóꞌchaxnim (informally named Vatira before its discovery) population of Atira-class asteroids. ꞌAylóꞌchaxnim has the smallest known aphelion and third-smallest known semi-major axis among all asteroids. With an absolute magnitude approximately 16.2, the asteroid is expected to be larger than in diameter. Discovery ꞌAylóꞌchaxnim was discovered by the Zwicky Transient Facility (ZTF) survey at the Palomar Observatory on 4 January 2020, by astronomers Bryce Bolin, Frank Masci, and Quanzhi Ye. The discovery formed part of a campaign for detecting interior-Earth asteroids (Atiras) using the wide-field ZTF camera on the 1.22-meter Samuel Oschin telescope at the Palomar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Naming Conventions
In ancient times, only the Sun and Moon, a few stars, and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered every year. Astronomers need to be able to assign systematic designations to unambiguously identify all of these objects, and at the same time give names to the most interesting objects, and where relevant, features of those objects. The International Astronomical Union (IAU) is the recognized authority in astronomy for assigning designations to celestial bodies such as stars, planets, and minor planets, including any surface features on them. In response to the need for unambiguous names for astronomical objects, it has created a number of systematic naming systems for objects of various sorts. Stars There are no more than a few thousand stars that appear sufficiently bright in Earth's sky to be visible to the naked eye. This repres ... [...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 MPC collects l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ellipsoid
An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the zero set of a polynomial of degree two in three variables. Among quadric surfaces, an ellipsoid is characterized by either of the two following properties. Every planar cross section is either an ellipse, or is empty, or is reduced to a single point (this explains the name, meaning "ellipse-like"). It is bounded, which means that it may be enclosed in a sufficiently large sphere. An ellipsoid has three pairwise perpendicular axes of symmetry which intersect at a center of symmetry, called the center of the ellipsoid. The line segments that are delimited on the axes of symmetry by the ellipsoid are called the ''principal axes'', or simply axes of the ellipsoid. If the three axes have different lengths, the figure is a triaxial elli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrostatic Equilibrium
In fluid mechanics, hydrostatic equilibrium (hydrostatic balance, hydrostasy) is the condition of a fluid or plastic solid at rest, which occurs when external forces, such as gravity, are balanced by a pressure-gradient force. In the planetary physics of Earth, the pressure-gradient force prevents gravity from collapsing the planetary atmosphere into a thin, dense shell, whereas gravity prevents the pressure-gradient force from diffusing the atmosphere into outer space. Hydrostatic equilibrium is the distinguishing criterion between dwarf planets and small solar system bodies, and features in astrophysics and planetary geology. Said qualification of equilibrium indicates that the shape of the object is symmetrically ellipsoid, where any irregular surface features are consequent to a relatively thin solid crust. In addition to the Sun, there are a dozen or so equilibrium objects confirmed to exist in the Solar System. Mathematical consideration For a hydrostatic fluid o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jupiter
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth the mass of the Sun. Jupiter is the third brightest natural object in the Earth's night sky after the Moon and Venus, and it has been observed since prehistoric times. It was named after the Roman god Jupiter, the king of the gods. Jupiter is primarily composed of hydrogen, but helium constitutes one-quarter of its mass and one-tenth of its volume. It probably has a rocky core of heavier elements, but, like the other giant planets in the Solar System, it lacks a well-defined solid surface. The ongoing contraction of Jupiter's interior generates more heat than it receives from the Sun. Because of its rapid rotation, the planet's shape is an oblate spheroid: it has a slight but noticeable bulge around the equator. The outer atmosphere i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
How I Killed Pluto And Why It Had It Coming
''How I Killed Pluto and Why It Had It Coming'' is the 2010 memoir by Mike Brown, the American astronomer most responsible for the reclassification of Pluto from planet to dwarf planet. Summary The memoir is an account of the events surrounding the redefinition of the term ''planet'' that eventually changed the status of Pluto. It chronicles the discovery of Eris, a dwarf planet then mistakenly thought to be larger than Pluto, located within the scattered disc, beyond Neptune's orbit. The replaying of events includes the adversarial challenging of long-held scientific beliefs between some of the world's leading astronomers, and the eventual 2006 International Astronomical Union's vote that removed Pluto from the list of Solar System planets. Reviews Reviews of the book have been generally positive, with James Kennedy of ''The Wall Street Journal'' calling the book a "brisk" and "enjoyable ... chronicle" of the tale of the search for new planets and the eventual demotion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceres (dwarf Planet)
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 cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Unnumbered Minor Planets
The following is a list of unnumbered minor planets in chronological order of their principal provisional designation. Contrary to their numbered counterparts, unnumbered minor planets have a poorly determined orbit due to insufficient observational data. This also includes lost minor planets which have not been observed for many years, or even decades. , the Minor Planet Center (MPC) accounts for 558,491 unnumbered minor planets which represent of the overall minor planet population. Unnumbered minor planets can be further divided into 111,001 single-opposition objects with short observation arcs, prone to mismatch and loss, and 447,490 objects that have been observed multiple times during opposition, when astrometric conditions are most favorable. The JPL Small-Body Database gives a running total of 561,837 unnumbered minor planets. The tables below contain 112 objects with a principal designation assigned between 1927 and 1993. Additional partial lists cover the period f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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