Minor planet


A minor planet is an astronomical object in direct orbit around the Sun that is neither a planet nor exclusively classified as a comet. Before 2006 the International Astronomical Union 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.
Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, and other trans-Neptunian objects. As of 2019, the orbits of 794,832 minor planets were archived at the Minor Planet Center, 541,128 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 been used, especially for larger objects such as those the International Astronomical Union has called dwarf planets since 2006. Historically, the terms asteroid, minor planet, and planetoid have been more or less synonymous. This terminology has become more complicated by the discovery of numerous minor planets beyond the orbit of Jupiter, especially trans-Neptunian objects that are generally not considered asteroids. A minor planet seen releasing gas may be dually classified as a comet.
Objects are called dwarf planets if their own 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.

Populations

Hundreds of thousands of minor planets have been discovered within the Solar System and thousands more are discovered each month. The Minor Planet Center has documented over 213 million observations and 794,832 minor planets, of which 541,128 have orbits known well enough to be assigned permanent official numbers. Of these, 21,922 have official names., the lowest-numbered unnamed minor planet is, and the highest-numbered named minor planet is 543315 Asmakhammari.
There are various broad minor-planet populations:
All astronomical bodies in the Solar System need a distinct designation. The naming of minor planets runs through a three-step process. First, a provisional designation is given upon discovery—because the object still may turn out to be a false positive or become lost later on—called a provisionally designated minor planet. After the observation arc is accurate enough to predict its future location, a minor planet is formally designated and receives a number. It is then a numbered minor planet. Finally, in the third step, it may be named by its discoverers. However, only a small fraction of all minor planets have been named. The vast majority are either numbered or have still only a provisional designation. Example of the naming process:
A newly discovered minor planet is given a provisional designation. For example, the provisional designation consists of the year of discovery and an alphanumeric code indicating the half-month of discovery and the sequence within that half-month. Once an asteroid's orbit has been confirmed, it is given a number, and later may also be given a name. The formal naming convention uses parentheses around the number, but dropping the parentheses is quite common. Informally, it is common to drop the number altogether, or to drop it after the first mention when a name is repeated in running text.
Minor planets that have been given a number but not a name keep their provisional designation, e.g. 1950 DA. Because modern discovery techniques are finding vast numbers of new asteroids, they are increasingly being left unnamed. The earliest discovered to be left unnamed was for a long time 1981 VA, now 3360 Syrinx; as of September 2008, this distinction is held by. On rare occasions, a small object's provisional designation may become used as a name in itself: the then unnamed gave its "name" to a group of objects that became known as classical Kuiper belt objects before it was finally named 15760 Albion in January 2018.
A few objects are cross-listed as both comets and asteroids, such as 4015 Wilson–Harrington, which is also listed as 107P/Wilson–Harrington.

Numbering

Minor planets are awarded an official number once their orbits are confirmed. With the increasing rapidity of discovery, these are now six-figure numbers. The switch from five figures to six figures arrived with the publication of the Minor Planet Circular of October 19, 2005, which saw the highest numbered minor planet jump from 99947 to 118161.

Naming

The first few asteroids were named after figures from Greek and Roman mythology but as such names started to dwindle the names of famous people, literary characters, discoverer's spouses, children, colleagues, and even television characters were used.

Gender

Eccentric

Discoverer's name

Languages

Physical properties of comets and minor planets

Commission 15 of the International Astronomical Union is dedicated to the Physical Study of Comets & Minor Planets.
Archival data on the physical properties of comets and minor planets are found in the PDS Asteroid/Dust Archive. This includes standard asteroid physical characteristics such as the properties of binary systems, occultation timings and diameters, masses, densities, rotation periods, surface temperatures, albedoes, spin vectors, taxonomy, and absolute magnitudes and slopes. In addition, European Asteroid Research Node, an association of asteroid research groups, maintains a Data Base of Physical and Dynamical Properties of Near Earth Asteroids.
Most detailed information is available from :Category: Minor planets visited by spacecraft and :Category: Comets visited by spacecraft.