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A critical-list minor planet (''critical list numbered object'' or ''critical object'') is a numbered
minor planet
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 ...
whose
orbit
In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...
and
position
Position often refers to:
* Position (geometry), the spatial location (rather than orientation) of an entity
* Position, a job or occupation
Position may also refer to:
Games and recreation
* Position (poker), location relative to the dealer
* ...
is especially in need of improvement.
The
IAU
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...
's
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
...
(MPC) regularly publishes a list of these critical objects in their ''
Minor Planet Electronic Circular
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 list typically contains
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.
...
s that have been
observed
Observation is the active acquisition of information from a primary source. In living beings, observation employs the senses. In science, observation can also involve the perception and recording of data (information), data via the use of scienti ...
at a small number of apparitions, especially on
opposition
Opposition may refer to:
Arts and media
* ''Opposition'' (Altars EP), 2011 EP by Christian metalcore band Altars
* The Opposition (band), a London post-punk band
* ''The Opposition with Jordan Klepper'', a late-night television series on Comed ...
, or that have not been adequately observed for more than 10 years, while other observatories create their own, customized lists.
The MPC also lists currently observable critical objects on their website,
providing differently formatted lists of
orbital element
Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same ...
s to the worldwide
astrometric
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way.
Histor ...
community.
, the MPC includes more than a thousand objects in their critical list, half of them being either
near-Earth asteroids
A near-Earth object (NEO) is any small Solar System body whose orbit brings it into proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). ...
or
distant minor planets
A distant minor planet, or ''distant object'', is any minor planet found beyond Jupiter in the outer Solar System that is not commonly thought of as an "asteroid". The umbrella term is used by IAU's Minor Planet Center (MPC), which is responsibl ...
which account for 674 and 192 critical objects, respectively.
List
The lowest numbered critical-list objects are:
*
1915 Quetzálcoatl
1915 Quetzálcoatl, provisional designation , is a very eccentric, stony asteroid classified as near-Earth object, about half a kilometer in diameter. It was discovered on 9 March 1953, by American astronomer Albert George Wilson at Palomar Obs ...
*
2135 Aristaeus
*
3362 Khufu
3362 Khufu is a near-Earth asteroid. It was discovered by R. Scott Dunbar and Maria A. Barucci at the Palomar Observatory in San Diego County, California, on 30 August 1984. Its provisional designation was 1984 QA. It is named after Khufu, an ...
*
3753 Cruithne
3753 Cruithne is a Q-type, Aten asteroid in orbit around the Sun in 1:1 orbital resonance with Earth, making it a co-orbital object. It is an asteroid that, relative to Earth, orbits the Sun in a bean-shaped orbit that effectively describes a ...
*
(4688) 1980 WF
*
5335 Damocles
(5335) Damocles , provisional designation , is a centaur and the namesake of the damocloids, a group of minor planets which may be inactive nuclei of the Halley-type and long-period comets. It was discovered on 18 February 1991, by Aus ...
*
(5590) 1990 VA
*
7066 Nessus
7066 Nessus is a very red centaur on an eccentric orbit, located beyond Saturn in the outer Solar System. It was discovered on 26 April 1993, by astronomers of the Spacewatch program at the Kitt Peak National Observatory in Tucson, Arizona. The ...
*
(8014) 1990 MF
(8014) 1990 MF is a sub-kilometer near-Earth object and potentially hazardous asteroid in the Apollo group. It was discovered by American astronomer Eleanor Helin
Eleanor Francis "Glo" Helin (née Francis, 19 November 1932 – 25 January 2 ...
*
10370 Hylonome
10370 Hylonome (; '' prov. designation'': ) is a minor planet orbiting in the outer Solar System. The dark and icy body belongs to the class of centaurs and measures approximately in diameter. It was discovered on 27 February 1995, by English a ...
*
14827 Hypnos
14827 Hypnos ('' prov. designation:'' ) is a highly eccentric, sub-kilometer-sized carbonaceous asteroid that is thought to be an extinct comet. It is classified as near-Earth object and potentially hazardous asteroid of the Apollo group.
The a ...
*
*
(15789) 1993 SC
*
*
(15809) 1994 JS
*
*
*
*
*
19521 Chaos
*
*
*
*
20461 Dioretsa
20461 Dioretsa is a centaur and damocloid on a retrograde, cometary-like orbit from the outer Solar System. It was discovered on 8 June 1999, by members of the LINEAR team at the Lincoln Laboratory Experimental Test Site near Socorro, New Mexico ...
See also
*
Distant minor planet
A distant minor planet, or ''distant object'', is any minor planet found beyond Jupiter in the outer Solar System that is not commonly thought of as an "asteroid". The umbrella term is used by IAU's Minor Planet Center (MPC), which is responsibl ...
*
Lost minor planet
A minor planet is "lost" when today's observers cannot find it, because its location is too uncertain to target observations. This happens if the orbital elements of a minor planet are not known accurately enough, typically because the observat ...
*
Unusual minor planet In planetary science, the term unusual minor planet, or ''unusual object'', is used for a minor planet that possesses an unusual physical or orbital characteristic. For the Minor Planet Center (MPC), which operates under the auspices of the Internat ...
References
External links
MPEC 1998-G21 : CRITICAL-LIST MINOR PLANETS Minor Planet Circular (1998)
Asteroid orbit determination using Bayesian probabilities Karri Muinonen, Edward Bowell (1993)
{{Small Solar System bodies
Minor planets