149 Medusa

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149 Medusa
149Medusa (Lightcurve Inversion).png
A three-dimensional model of 149 Medusa based on its light curve.
Discovered by Henri Joseph Perrotin
Discovery date September 21, 1875
Named after
Main belt
Orbital characteristics[2][3]
Epoch December 31, 2006 (JD 2454100.5)
Aphelion 346.542 Gm (2.316 AU)
Perihelion 304.026 Gm (2.032 AU)
325.284 Gm (2.174 AU)
Eccentricity 0.065
1171.128 d (3.21 yr)
20.18 km/s
Inclination 0.937°
Physical characteristics
Dimensions 19.7 km
Mass 8.0×1015 kg
Mean density
2.0 g/cm³
Equatorial surface gravity
0.0055 m/s²
Equatorial escape velocity
0.0104 km/s
26.038 h [4]
Temperature ~ 189 K

149 Medusa is a bright-coloured, stony main-belt asteroid that was discovered by French astronomer J. Perrotin on September 21, 1875, and named after the Gorgon Medusa, a snake-haired monster in Greek mythology.

When it was discovered, Medusa was by far the smallest asteroid found (although this was not known at that time). Since then, many thousands of smaller asteroids have been found. It was also the closest asteroid to the Sun discovered up to that point, beating the long-held record of 8 Flora. It remained the closest asteroid to the Sun until 433 Eros and 434 Hungaria were found in 1898, leading to the discovery of two new families of asteroids inward from the 4:1 Kirkwood gap which forms the boundary of the main belt.

Photometric observations of this asteroid at the Organ Mesa Observatory in Las Cruces, New Mexico, during 2010 gave a light curve with a rather long rotation period of 26.038 ± 0.002 hours and a brightness variation of 0.56 ± 0.03 in magnitude.[4]


  1. ^ "Discovery Circumstances: Numbered Minor Planets (1)-(5000)". IAU-Minor Planet Center. Retrieved September 2015. 
  2. ^ ftp://ftp.lowell.edu/pub/elgb/astorb.html
  3. ^ Yeomans, Donald K., "149 Medusa", JPL Small-Body Database Browser (NASA Jet Propulsion Laboratory), retrieved 2013-03-30. 
  4. ^ a b Pilcher, Frederick (April 2011), "Rotation Period Determinations for 25 Phocaea, 140 Siwa, 149 Medusa 186 Celuta, 475 Ocllo, 574 Reginhild, and 603 Timandra", Bulletin of the Minor Planets Section of the Association of Lunar and Planetary Observers 38 (2), pp. 76–78, Bibcode:2011MPBu...38...76P. 

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