(4953) 1990 MU ('' prov. designation:'' ) is a large Earth-crossing asteroid (ECA) belonging to the

Apollo Apollo, grc, Ἀπόλλωνος, Apóllōnos, label=genitive , ; , grc-dor, Ἀπέλλων, Apéllōn, ; grc, Ἀπείλων, Apeílōn, label=Arcadocypriot Greek, ; grc-aeo, Ἄπλουν, Áploun, la, Apollō, la, Apollinis, label= ...

group of

near-Earth object 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). ...

s which also cross the orbits of

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

and

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...

. At approximately 3 km in diameter, it is one of the largest known ECAs. It has been assigned a permanent number from the

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 ...

(4953) indicating that its orbit has been very well determined. With an

observation arc In observational astronomy, the observation arc (or arc length) of a Solar System body is the time period between its earliest and latest observations, used for tracing the body's path. It is usually given in days or years. The term is mostly use ...

of 45 years, the asteroid's trajectory and uncertainty regions are well known through to the year 2186.

Description

was first observed over three nights in 1990. By itself, this was not enough for the asteroid to be given a permanent number since the orbit could not be calculated accurately enough for the object to be subsequently recovered. However, the object was precovered by the

Anglo-Australian Near-Earth Asteroid Survey The Anglo-Australian Near-Earth Asteroid Survey (AANEAS) operated from 1990 to 1996, becoming one of the most prolific programs of its type in the world. Apart from leading to the discovery of 38 near-Earth asteroids, 9 comets, 63 supernovae, severa ...

on six photographic plates from the

UK Schmidt Telescope The UK Schmidt Telescope (UKST) is a 1.24 metre Schmidt telescope operated by the Australian Astronomical Observatory (formerly the Anglo-Australian Observatory); it is located adjacent to the 3.9 metre Anglo-Australian Telescope at S ...

dating back to 1974. This technique has more success with the

Amor group Amor Group was Scotland's largest independent business technology company before being acquired by Lockheed Martin in September 2013. The business was formed after a £28 million management buyout of Glasgow based Real Time Engineering Ltd. an ...

of asteroids which do not cross the orbit of the Earth and consequently have long periods of

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 ...

when they can be observed. In this respect the Apollo asteroid is somewhat unusual. has an Earth minimum orbit intersection distance (MOID) of , which is close enough to classify it as a

potentially hazardous asteroid A potentially hazardous object (PHO) is a near-Earth object – either an asteroid or a comet – with an orbit that can make close approaches to the Earth and is large enough to cause significant regional damage in the event of impact. They are ...

(PHA). It will make a close approach to Earth on 6 June 2027 at , becoming as bright as apparent magnitude 9.7 on 8 June 2027, and even closer on 5 June 2058 at . It also made a close approach to Venus on 5 October 2012 at and will again on 3 September 2041 at . has made close approaches to Earth in the past; in June 1996 it approached within 0.25 AU and in May 1990 it approached to 0.1418 AU. The Earth MOID of has been decreasing (becoming more hazardous) during the 20th century, while the Venus MOID (0.0455) has been increasing. Besides its original discovery at

Siding Spring Observatory Siding Spring Observatory near Coonabarabran, New South Wales, Australia, part of the Research School of Astronomy & Astrophysics (RSAA) at the Australian National University (ANU), incorporates the Anglo-Australian Telescope along with a coll ...

in Australia, has also been studied by radar at

Goldstone Observatory The Goldstone Deep Space Communications Complex (GDSCC), commonly called the Goldstone Observatory, is a satellite ground station located in Fort Irwin in the U.S. state of California. Operated by NASA's Jet Propulsion Laboratory (JPL), its main ...

in California, and

Arecibo Observatory The Arecibo Observatory, also known as the National Astronomy and Ionosphere Center (NAIC) and formerly known as the Arecibo Ionosphere Observatory, is an observatory in Barrio Esperanza, Arecibo, Puerto Rico owned by the US National Science F ...

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...

. Lightcurves have been obtained at La Silla Observatory in Chile. The

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

of was measured by the ExploreNEOs project of the

Spitzer Space Telescope The Spitzer Space Telescope, formerly the Space Infrared Telescope Facility (SIRTF), was an infrared space telescope launched in 2003. Operations ended on 30 January 2020. Spitzer was the third space telescope dedicated to infrared astronomy, f ...

in August 2009. The result obtained was 0.79 and was the second highest albedo measured by the project. However, ExploreNEO do not believe this is a plausible figure, they state that the albedo of an NEO is not likely to be much over 0.5 and their measurement uncertainty is "around a factor of 2". The ''Gaia'' mission of the

European Space Agency , owners = , headquarters = Paris, Île-de-France, France , coordinates = , spaceport = Guiana Space Centre , seal = File:ESA emblem seal.png , seal_size = 130px , image = Views in the Main Control Room (1205 ...

, launched in December 2013, has been tasked with measuring the

Yarkovsky effect The Yarkovsky effect is a force acting on a rotating body in space caused by the anisotropic emission of thermal photons, which carry momentum. It is usually considered in relation to meteoroids or small asteroids (about 10 cm to 10 km i ...

near-Earth asteroid 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). ...

s (NEAs). The Yarkovsky effect is a small non-gravitational force on rotating bodies that can affect their trajectories. Its effect on small bodies like asteroids can be significant and needs to be taken into account in predicting an asteroid's position. has been selected as one of the most promising NEAs for this measurement by ''Gaia''.

References

External links

* * * {{DEFAULTSORT:1990 MU 004953 004953 004953 Discoveries by Robert H. McNaught 004953 19900623

Description

See also

References

External links