|Discovered by||Johann Palisa|
|Discovery date||January 18, 1882|
|Minor planet category||Main belt (Eos)|
|Epoch 30 January 2005 (JD 2453400.5)|
|Aphelion||496.912 Gm (3.322 AU)|
|Perihelion||404.104 Gm (2.701 AU)|
|Semi-major axis||450.508 Gm (3.011 AU)|
|Orbital period||1908.778 d (5.23 a)|
|Average orbital speed||17.16 km/s|
|Longitude of ascending node||141.959°|
|Argument of perihelion||196.03°|
|Dimensions||103.52 ± 5.60 km|
|Mass||(5.87 ± 0.34) × 1018 kg|
|Mean density||10.10 ± 1.74 g/cm3|
|Rotation period||10.436 h|
|Absolute magnitude (H)||7.67|
221 Eos // is a large main-belt asteroid that was discovered by Johann Palisa on January 18, 1882, in Vienna. In 1884, it was named after Eos, the Greek goddess of dawn, to honour the opening of a new observatory that was hoped to bring about a new dawn for Viennese astronomy.
Based upon its spectral characteristics, this object is classified as a K-type asteroid. The orbital properties show it to be a member of the extensive Eos asteroid family, which is named after it.
- Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science 73: 98-118, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
- Lutz D. Schmadel, Dictionary of Minor Planet Names, p.35
- Veeder, G. J. et al. (March 1995), "Eos, Koronis, and Maria family asteroids: Infrared (JHK) photometry", Icarus 114: 186–196, Bibcode:1995Icar..114..186V, doi:10.1006/icar.1995.1053, retrieved 2013-04-06.
- The Asteroid Orbital Elements Database
- Minor Planet Discovery Circumstances
- Asteroid Lightcurve Data File
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