85 Io
Encyclopedia
85 Io is a large, dark main-belt asteroid
of the C
spectral class. It is probably a primitive body composed of carbonate
s. Like 70 Panopaea
it orbits within the Eunomia asteroid family
but it is not related to the shattered parent body.
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.[1] This gives an axial tilt
of about 125° or 115°, respectively. Its shape is quite regular.
It was discovered by C. H. F. Peters
on September 19, 1865, and named after Io
, a lover of Zeus
in Greek mythology
.
An Ionian diameter of 178 kilometres was measured from an occultation
of a star
on December 10, 1995.[4] Another asteroid occultation of Io (magnitude 13.2) occurred on March 12, 2009, from the eastern USA, with the star 2UCAC 35694429
(magnitude 13.8).
Io
is also the name of the volcanic satellite
of Jupiter
. With a two-digit number and a two-letter name, 85 Io has the shortest designation of all minor planets.
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
of the C
C-type asteroid
C-type asteroids are carbonaceous asteroids. They are the most common variety, forming around 75% of known asteroids, and an even higher percentage in the outer part of the asteroid belt beyond 2.7 AU, which is dominated by this asteroid type...
spectral class. It is probably a primitive body composed of carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
s. Like 70 Panopaea
70 Panopaea
70 Panopaea is a large main belt asteroid. Its orbit is close to those of the Eunomia asteroid family; however, Panopaea is a dark, primitive carbonaceous C-type asteroid in contrast to the S-type asteroids of the Eunomian asteroids....
it orbits within the Eunomia asteroid family
Eunomia family
The Eunomia family of asteroids is a large grouping of S-type asteroids named after the Greek goddess Eunomia. It is the most prominent family in the intermediate main belt...
but it is not related to the shattered parent body.
Io is a retrograde rotator, with its pole pointing towards one of ecliptic coordinates
Ecliptic coordinate system
The ecliptic coordinate system is a celestial coordinate system that uses the ecliptic for its fundamental plane. The ecliptic is the path that the sun appears to follow across the celestial sphere over the course of a year. It is also the intersection of the Earth's orbital plane and the celestial...
(β, λ) = (-45°, 105°) or (-15°, 295°) with a 10° uncertainty.[1] This gives an axial tilt
Axial tilt
In astronomy, axial tilt is the angle between an object's rotational axis, and a line perpendicular to its orbital plane...
of about 125° or 115°, respectively. Its shape is quite regular.
It was discovered by C. H. F. Peters
Christian Heinrich Friedrich Peters
Christian Heinrich Friedrich Peters was a German-American astronomer, and one of the first to discover asteroids....
on September 19, 1865, and named after Io
Io (mythology)
Io was, in Greek mythology, a priestess of Hera in Argos, a nymph who was seduced by Zeus, who changed her into a heifer to escape detection. His wife Hera set ever-watchful Argus Panoptes to guard her, but Hermes was sent to distract the guardian and slay him...
, a lover of Zeus
Zeus
In the ancient Greek religion, Zeus was the "Father of Gods and men" who ruled the Olympians of Mount Olympus as a father ruled the family. He was the god of sky and thunder in Greek mythology. His Roman counterpart is Jupiter and his Etruscan counterpart is Tinia.Zeus was the child of Cronus...
in Greek mythology
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
.
An Ionian diameter of 178 kilometres was measured from an occultation
Occultation
An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The word is used in astronomy . It can also refer to any situation wherein an object in the foreground blocks from view an object in the background...
of a star
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
on December 10, 1995.[4] Another asteroid occultation of Io (magnitude 13.2) occurred on March 12, 2009, from the eastern USA, with the star 2UCAC 35694429
(magnitude 13.8).
Io
Io (moon)
Io ) is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of , the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus....
is also the name of the volcanic satellite
Natural satellite
A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....
of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
. With a two-digit number and a two-letter name, 85 Io has the shortest designation of all minor planets.
| Conjunction to sun | stationary, then retrograde | Opposition | Minimal distance (AE) | Maximum brightness (mag) | stationary, then prograde |
|---|---|---|---|---|---|
| 27. April 2004 | 31.October 2004 | 23. December 2004 | 1,92017 AE | 12,3 mag | 11. February 2005 |
| 3.August 2005 | 9. . January 2006 | 5. March 2006 | 2,14389 AE | 11,8 mag | 25. April 2006 |
| 17.October 2006 | 26. April 2007 | 9.June 2007 | 1,38393 AE | 12,1 mag | 26.July 2007 |
| 7. March 2008 | 6.October 2008 | 22.November 2008 | 1,61470 AE | 10,7 mag | 9. . January 2009 |
| 8.July 2009 | 17. December 2009 | 12. February 2010 | 2,19864 AE | 11,1 mag | 3. April 2010 |
| 21.September 2010 | 15. March 2011 | 30. April 2011 | 1,68623 AE | 12,2 mag | 20.June 2011 |
| 7. . January 2012 | 31.August 2012 | 12.October 2012 | 1,28465 AE | 11,1 mag | 19.November 2012 |
| 9.June 2013 | 25.November 2013 | 20. . January 2014 | 2,13519 AE | 10,1 mag | 12. March 2014 |
| 29.August 2014 | 10. February 2015 | 1. April 2015 | 1,95222 AE | 12,2 mag | 22.May 2015 |
| 22.November 2015 | 30.June 2016 | 14.August 2016 | 1,16222 AE | 11,6 mag | 17.September 2016 |
| 3.May 2017 | 3.November 2017 | 26. December 2017 | 1,95048 AE | 10,2 mag | 15. February 2018 |
| 6.August 2018 | 13. . January 2019 | 9. March 2019 | 2,12957 AE | 11,8 mag | 28. April 2019 |
| 21.October 2019 | 2.May 2020 | 14.June 2020 | 1,34977 AE | 12,0 mag | 30.July 2020 |
See also
- List of Solar System objects by size