85 Io is a carbonaceous
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.
...
in the central region of the
asteroid belt, approximately 170 kilometers in diameter. It is an identified
Eunomian interloper.
Discovery and naming
It was discovered by
C. H. F. Peters
Christian Heinrich Friedrich Peters (September 19, 1813 – July 18, 1890) was a German–American university teacher and astronomer at the Litchfield Observatory of Hamilton College, New York, and a pioneer in the study and visual discovery of ...
on 19 September 1865, and named after
Io, a lover of
Zeus
Zeus or , , ; grc, Δῐός, ''Diós'', label=Genitive case, genitive Aeolic Greek, Boeotian Aeolic and Doric Greek#Laconian, Laconian grc-dor, Δεύς, Deús ; grc, Δέος, ''Déos'', label=Genitive case, genitive el, Δίας, ''D ...
in
Greek mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical co ...
.
Io is also the name of the
volcanic
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most often found where tectonic plates a ...
satellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...
of
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
. With a two-digit number and a two-letter name, 85 Io has the shortest designation of all minor planets.
Orbit and physical characteristics
Io is a
retrograde rotator, with its pole pointing towards one of
ecliptic coordinates (β, λ) = (-45°, 105°) or (-15°, 295°) with a 10° uncertainty.
This gives an
axial tilt
In astronomy, axial tilt, also known as obliquity, is the angle between an object's rotational axis and its orbital axis, which is the line perpendicular to its orbital plane; equivalently, it is the angle between its equatorial plane and orbi ...
of about 125° or 115°, respectively. Its shape is quite regular.
In the
SMASS classification
An asteroid spectral type is assigned to asteroids based on their emission spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally differentiat ...
, ''Io'' is a carbonaceous
C-type asteroid, which means that it is probably a primitive body composed of
carbonate
A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate g ...
s. Like
141 Lumen
Lumen (minor planet designation: 141 Lumen) is a carbonaceous asteroid from the intermediate asteroid belt
The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. I ...
it is an
interloper
Interloper, Interlopers or The Interlopers may refer to:
Entertainment
* '' The Interloper: Lee Harvey Oswald Inside the Soviet Union'', a 2013 book by Peter Savodnik
* Interloper (comics), a fictional character in the Marvel Comics universe
* I ...
that orbits within the
Eunomia asteroid family but it is not related to the shattered parent body.
An Ionian diameter of 178 kilometres was measured from an
occultation
An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...
of a
star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
on 10 December 1995.
Another
asteroid occultation of Io (magnitude 13.2) occurred on 12 March 2009, from the eastern
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
, with the star 2UCAC 35694429
(magnitude 13.8).
[http://www.asteroidoccultation.com/2009_03/0312_85_20455.htm ]
See also
*
List of Solar System objects by size
Notes
References
External links
Shapes and rotational properties of thirty asteroids from photometric data, Torppa (2003) *
*
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000085
Discoveries by Christian Peters
Named minor planets
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