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85 Io
From Wikipedia, the free encyclopedia
| Discovery | |
|---|---|
| Discovered by: | C. H. F. Peters |
| Discovery date: | September 19, 1865 |
| Alternative names: | A899 LA; A899 UA |
| Minor planet category: | Main belt |
| Orbital characteristics | |
| Epoch March 6, 2006 (JD 2453800.5) | |
| Aphelion distance: | 473.341 Gm (3.164 AU) |
| Perihelion distance: | 320.334 Gm (2.141 AU) |
| Semi-major axis: | 396.837 Gm (2.652 AU) |
| Eccentricity: | 0.193 |
| Orbital period: | 1578.081 d (4.32 a) |
| Avg. orbital speed: | 18.12 km/s |
| Mean anomaly: | 206.947° |
| Inclination: | 11.967° |
| Longitude of ascending node: | 203.440° |
| Argument of perihelion: | 122.293° |
| Physical characteristics | |
| Dimensions: | 180×160×160 km[1][4] |
| Mass: | ~3.4×1018 (estimate) |
| Mean density: | ~1.4 g/cm³ (estimate)[5] |
| Equatorial surface gravity: | ~0.028 m/s² (estimate) |
| Escape velocity: | ~0.07 km/s (estimate) |
| Rotation period: | 0.2864 d (6.875 h) [2] |
| Albedo: | 0.067 [3] |
| Temperature: | ~172 K max: 272K (-2° C) |
| Spectral type: | C-type asteroid |
| Absolute magnitude: | 7.61 |
85 Io (eye'-oh) is a large, dark Main belt asteroid of the C spectral class. It is probably a primitive body composed of carbonates. 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].
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.
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J. Torppa et al Shapes and rotational properties of thirty asteroids from photometric data, Icarus, Vol. 164, p. 346 (2003).
- PDS lightcurve data
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A. Erikson Photometric observations and modelling of the asteroid 85 Io in conjunction with data from an occultation event during the 1995-96 apparition, Planetary and Space Science, Vol. 47, p. 327 (1999).
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G. A. Krasinsky et al Hidden Mass in the Asteroid Belt, Icarus, Vol. 158, p. 98 (2002).
| 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 |
| Minor planets | ||
|---|---|---|
| Previous minor planet | 85 Io | Next minor planet |
| List of asteroids | ||
Vulcanoids · Near-Earth asteroids · Main belt · Jupiter Trojans · Centaurs · Damocloids · Comets · Trans-Neptunians (Kuiper belt • Scattered disc • Oort cloud)
For other objects and regions, see Asteroid groups and families, Binary asteroids, Asteroid moons and the Solar System.
For a complete listing, see List of asteroids. See also Pronunciation of asteroid names and Meanings of asteroid names.