Minor planet

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Euler diagram showing the relationship between the objects within the solar system (excluding the sun).

Minor planet ( . English minor planets ) or planetoids are astronomical objects that are on a direct orbit sun move, but the criteria for classification as a planet not meet - because they have not cleared their orbits accordingly - and beyond even as a comet or meteoroid can be classified. Minor planets whose mass and gravity are sufficient to have acquired spherical shape are called dwarf planets . Minor planets can be asteroids like centaurs and Trojans , or trans-Neptunian objects like Kuiper belt objects . By 2019, the orbits of 794,832 minor planets had been determined. The first minor planet to be discovered was Ceres in 1801 .

Definition of terms

Historically, the terms asteroid , minor planet and planetoid are more or less synonymous. However, the problem has become more complicated because numerous minor planets have been discovered outside of Jupiter's orbit , but especially the orbit of Neptune , for which the term asteroids is not commonly used. There are also minor planets that “ outgas ” and are also classified as comets.

Before 2006, the IAU officially used the term minor planet . During the 2006 conference, a subdivision of the minor planets into dwarf planets and Small Solar System Bodies (SSSB) was introduced. Objects are called dwarf planets if their mass is sufficient to achieve hydrostatic equilibrium , which is often expressed by the fact that they are roughly spherical in shape. The IAU stipulated that the term 'minor planet' may continue to be used, but that the term ' small solar system body ' should be preferred, which, however, has not yet received any resonance in linguistic usage. The traditional distinction between minor planets and comets continues to be used for numbering and naming .

classification

Minor planets can be divided into different categories mainly according to the areas of their occurrence:

  • Asteroids
    • Near-Earth asteroids are those asteroids whose orbit brings them within Mars orbit. For further subdivisions of these according to their path distances are used:
      • Aten asteroids have a semiaxis that is less than one orbit of the earth and whose aphelion (furthest distance from the sun) is greater than 0.983 AU.
      • Cupid asteroids are those near-Earth asteroids that come from outside the Earth orbit but do not cross it. Their perihelion is less than 1.382 (or, according to another definition, 1.300) AU and greater than 1.017 AU.
      • Apollo asteroids are those asteroids whose major axis is larger than that of Earth, while their perihelion distance to Earth is no more than 1.017 AU. Just like the Aten asteroids, they cross Earth orbit.
      • Atira (Apohele) asteroids move within the Earth's perihelion distance and are therefore entirely within Earth orbit.
    • Asteroids of the Asteroid Belt : the original and best known group of asteroids or minor planets.
    • Planet Trojans move around Lagrange points 4 and 5, 60 ° in front of and behind the planet, respectively.
      • The Mars Trojans share the orbit with Mars.
      • The Jupiter Trojans are asteroids that share Jupiter's orbit.
      • The Uranus Trojans have no long-term stable orbits because of the orbital disturbances caused by Saturn and Jupiter. So far only one such object is known.
      • Neptune Trojans are celestial bodies that share Neptune's orbit and are gravitationally bound to him. Although only a few are known, there is evidence that they are more numerous than both the asteroids in the asteroid belt and the Jupiter Trojans.
    • Centaurs are celestial bodies located in the outer solar system between the orbits of Jupiter and Neptune. Due to the gravitational influence of the gas giants, they have unstable orbits. So they must have come from somewhere else, possibly from outside the orbit of Neptune.
  • Trans- Neptunian objects are celestial bodies whose orbit is outside of the Neptunian orbit.

designation

The Minor Planet Center registered until the end of June 2016, 152 million observations of nearly 719,000 objects, of which about 715,000 were roughly classified as minor planets and 4,000 comets, of which had, in turn, almost 470,000 sufficiently precise orbit determination, making them permanent official numbers assigned could become. Over 20,000 of these minor planets had been given official names at the same time.

numbering

A newly discovered minor planet is given a provisional designation (such as 2002 AT 4 ), which consists of the year of discovery and an alphanumeric code , the alphanumeric code indicating the half-month of the discovery and the sequencing within this half-month. As soon as the asteroid orbit is known, it is given a number as a name and can later be given a name (such as (433) Eros ). With the increasing speed of new discoveries, it has become six-digit numbering. The change from five to six digits happened with the circular Minor Planet Circular (MPC) of October 19, 2005, when the number of numbered minor planets grew from 99,947 to 118,161. Formal nomenclature uses parentheses around numbers, but it is common to leave them out. Informally, the number is often completely omitted or is no longer in a text after the first mention if the name is repeated there.

Minor planets that have been given a number instead of a name keep their temporary designation, e.g. B. (29075) 1950 DA . As modern discovery methods find large numbers of new asteroids, more and more are not named. The oldest discovery, which has long remained unnamed, is (3360) 1981 VA, now called (3360) Syrinx ; since September 2008 the oldest of its kind (3708) is 1974 FV 1 . The provisional designation of a small object itself is rarely used as a name: the long unnamed (15760) Albion 1 was provisionally called (15760) 1992 QB 1 until 2018 and that onomatopoeic (“QB one”) led to the name “ Cubewanos ” of a group the Kuiper Belt Objects known as Classic Kuiper Belt Objects .

A few objects are listed as both asteroids and comets, such as B. (4015) Wilson-Harrington , also listed as 107P / Wilson-Harrington .

Sources of names

The first asteroids were named after characters from Greek and Roman mythology , but when those names ran out, names of well-known people, literary figures, spouses and children of the explorers, as well as names from film and television were used.

The first asteroid to be given a non-mythological name was (20) Massalia , which was named after the Greek name of the city of Marseille . The one who was the first to get a name that was not at all classical was (45) Eugenia , named after the wife of Napoleon III. , Empress Eugénie de Montijo . For a time only feminine (or feminized) names were used; Alexander von Humboldt was the first man an asteroid was named after, but his name was feminized to (54) Alexandra . This unspoken tradition remained until (334) Chicago was named; even then, effeminate names continued to appear for years.

As the number of asteroids went into the hundreds and eventually into the thousands, explorers had begun to give them increasingly arbitrary names. The first harbingers of this were (482) Petrina and (483) Seppina , who were named after the house dogs of the discoverers. However, there was little controversy in this regard until 1971 when (2309) Mr. Spock (the name of the discoverer's cat) was awarded. Although the IAU subsequently banned the use of pet names, unusual asteroid names such as. B. (4321) Zero , (6042) Cheshirecat , (9007) James Bond , (13579) Allodd and (24680) Alleven and (26858) Misterrogers are still proposed and accepted.

An established rule is that, unlike comets, minor planets may not be named after whoever discovered them. One way to get around this rule is to name other minor planet explorers for the asteroids. An exception to this rule is (96747) Crespodasilva , named after its discoverer Lucy d'Escoffier Crespo da Silva because she committed suicide shortly after its discovery at the age of 22.

From the beginning, names were adapted to different languages. (1) Ceres , where Ceres was the Anglo-Latin name, was actually named Cerere , which corresponds to the Italian form of the name. Arabic, German, French, and Hindi use forms similar to English, while Russian uses Tserera , which is similar to Italian. In Greek, the name was translated to Δήμητρα ( Demeter ), the Greek equivalent of the Roman goddess Ceres. During the early days when asteroids were named after Roman figures, they were generally translated into Greek; other examples are Ἥρα ( Hera ) for Juno , Ἑστία ( Hestia ) for Vesta , Χλωρίς ( Chloris ) for Flora and Πίστη ( Pistis ) for Fides . In Chinese they are not named after the names of the Chinese forms of deities, but typically have one or two syllables for the figure of the deity or person, followed by 神  - "God / Goddess" or 女  - "Woman" if only one syllable , plus 星  - “star / planet”, so most asteroid names are written using three Chinese characters. Consequently, Ceres becomes 谷 神 星  - "Grain Goddess Planet", Pallas is 智 神 星  - "Wisdom Goddess Planet", etc.

Special rules

There are populations of minor planets for which rules have been developed regarding the source of names, e.g. B. Centaurs (orbiting between Saturn and Neptune) are all named after mythological centaurs ; Jupiter Trojans after Heroes of the Trojan War ; resonant trans -Neptunian objects according to underworld beings and non- resonant TNO according to creation deities.

Acquisition of physical properties

Commission 15 of the International Astronomical Union is responsible for the physical research of comets and minor planets. The data on minor planets and comets can be found in the PDS Asteroid / Dust Archive - the properties of binary systems, occultation times and diameter, mass, density, rotation period, surface temperature, albedo, spin vector, taxonomy and absolute size and slope. In addition, the European Asteroid Research Node (EARN), an association of the asteroid research groups, maintains a database of the physical and dynamic properties of near-Earth asteroids.

See also

Web links

Wiktionary: Minor planet  - explanations of meanings, word origins, synonyms, translations

Remarks

  1. ↑ Here 谷  - "valley" as a common simplification ( abbreviation ) of 穀  - used "grain".

Individual evidence

  1. ↑ a b c Minor Planet Statistics . Minor Planet Center. Retrieved March 17, 2020.
  2. ↑ David W. Hughes, Brian G. Marsden: Planet, asteroid, minor planet: A case study in astronomical nomenclature . In: Journal of Astronomical History and Heritage . tape 10 , March 2007, p. 21-30 .
  3. ↑ asteroid. In: MSN Encarta. Archived from the original on November 1, 2009 ; Retrieved May 5, 2008 .
  4. ↑ a b IAU 2006 General Assembly: Result of the IAU Resolution votes . International Astronomical Union, August 24, 2006, accessed May 5, 2008 (press release).
  5. ↑ Q: Is the term minor planet still to be used? In: Pluto and the Developing Landscape of Our Solar System. The discovery of Pluto. International Astronomical Union , August 24, 2006. May 8, 2008.
  6. ↑ Unusual Minor Planets . Minor Planet Center. Retrieved December 23, 2011.
  7. ↑ Neptune trojans, Jupiter trojans
  8. ^ J. Horner, NW Evans, ME Bailey: Simulations of the Population of Centaurs I: The Bulk Statistics . In: Monthly Notices of the Royal Astronomical Society . 354, No. 3, 2004, pp. 798-810. arxiv : astro-ph / 0407400 . bibcode : 2004MNRAS.354..798H . doi : 10.1111 / j.1365-2966.2004.08240.x .
  9. ↑ JPL: How Many Solar System Bodies . In: JPL Solar System Dynamics . NASA. Retrieved June 11, 2014.
  10. ↑ Dr. David Jewitt: Classical Kuiper Belt Objects . David Jewitt / UCLA. Retrieved July 1, 2013.
  11. ^ Lutz Schmadel: Dictionary of Minor Planet Names , 6th edition, Springer,, ISBN 978-3-642-29718-2 , p. 15.
  12. ^ Naming Astronomical Objects . International Astronomical Union. Retrieved July 1, 2013.
  13. ↑ NASA JPL Small-Body Database Browser on 96747 Crespodasilva
  14. ↑ Staff: Lucy Crespo da Silva, 22, a senior, dies in fall , Hubble News Desk. November 28, 2000. Retrieved April 15, 2008. 
  15. ^ Division III Commission 15 Physical Study of Comets & Minor Planets . International Astronomical Union (IAU). September 29, 2005. Archived from the original on March 28, 2010. Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved March 22, 2010. @1@ 2Template: Webachiv / IABot / www.iau.org
  16. ^ Physical Properties of Asteroids . Retrieved November 24, 2014.
  17. ^ The Near-Earth Asteroids Data Base . Archived from the original on August 21, 2014. Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved November 24, 2014. @1@ 2Template: Webachiv / IABot / earn.dlr.de