980 Anacostia is a
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 ...
orbiting the
Sun
The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...
that was discovered by American astronomer
George Henry Peters on 21 November 1921. The name recognizes the
Anacostia River
The Anacostia River is a river in the Mid-Atlantic states, Mid Atlantic region of the United States. It flows from Prince George's County, Maryland, Prince George's County in Maryland into Washington, D.C., where it joins with the Washington Ch ...
and an historic neighborhood of the same name in the city of Washington, D.C.
Measurements using the
adaptive optics
Adaptive optics (AO) is a technique of precisely deforming a mirror in order to compensate for light distortion. It is used in Astronomy, astronomical telescopes and laser communication systems to remove the effects of Astronomical seeing, atmo ...
system at the
W. M. Keck Observatory give a diameter of 70 ± 6 km. This is 23% smaller than the diameter estimated from the
IRAS
The Infrared Astronomical Satellite (Dutch language, Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a astronomical survey, survey of the entire night sky at infrared wavelengths. Launched on 25 Janu ...
observatory data. The size ratio between the major and minor axes is 1.09.
Polarimetric
Polarimetry is the measurement and interpretation of the polarization of transverse waves, most notably electromagnetic waves, such as radio or light waves. Typically polarimetry is done on electromagnetic waves that have traveled through or hav ...
study of this asteroid reveals anomalous properties that suggests the
regolith
Regolith () is a blanket of unconsolidated, loose, heterogeneous superficial deposits covering solid rock. It includes dust, broken rocks, and other related materials and is present on Earth, the Moon, Mars, some asteroids, and other terrestria ...
consists of a mixture of low and high
albedo
Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...
material. This may have been caused by fragmentation of an asteroid
substrate
Substrate may refer to:
Physical layers
*Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached
** Substrate (aquatic environment), the earthy material that exi ...
with the spectral properties of CO3/CV3
carbonaceous chondrites
Carbonaceous chondrites or C chondrites are a class of chondritic meteorites comprising at least 8 known groups and many ungrouped meteorites. They include some of the most primitive known meteorites. The C chondrites represent only a small propor ...
.
References
External links
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Discoveries by George Peters
Named minor planets
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