149 Medusa

149 Medusa

A three-dimensional model of 149 Medusa based on its light curve.
Discovery
Discovered by	Henri Joseph Perrotin
Discovery date	September 21, 1875
Designations
Named after	Medusa
Minor planet category	Main belt
Orbital characteristics
Epoch December 31, 2006 (JD 2454100.5)
Aphelion	346.542 Gm (2.316 AU)
Perihelion	304.026 Gm (2.032 AU)
Semi-major axis	325.284 Gm (2.174 AU)
Eccentricity	0.065
Orbital period	1171.128 d (3.21 yr)
Average orbital speed	20.18 km/s
Mean anomaly	284.523°
Inclination	0.937°
Longitude of ascending node	159.647°
Argument of perihelion	251.134°
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
Rotation period	26.038 h
Geometric albedo	0.10
Temperature	~ 189 K
Spectral type	S
Absolute magnitude (H)	10.79

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.