149 Medusa

149 Medusa
	A three-dimensional model of 149 Medusa based on its light curve.
Discovery [1]
Discovered by	Henri Joseph Perrotin
Discovery date	21 September 1875
Designations
MPC designation	(149) Medusa
Pronunciation	/mɪˈdjuːsə/[2]
Named after	Medusa
Minor planet category	Main belt
Orbital characteristics [3][4]
	Epoch 31 July 2016 (JD 2457600.5)
	Uncertainty parameter 0
Observation arc	124.55 yr (45493 d)
Aphelion	2.3169 AU (346.60 Gm)
Perihelion	2.03252 AU (304.061 Gm)
Semi-major axis	2.17472 AU (325.333 Gm)
Eccentricity	0.065386
Orbital period	3.21 yr (1171.4 d)
Average orbital speed	20.18 km/s
Mean anomaly	280.686°
Mean motion	0° 18m 26.374s / day
Inclination	0.93927°
Longitude of ascending node	159.615°
Argument of perihelion	250.609°
Earth MOID	1.04123 AU (155.766 Gm)
Jupiter MOID	2.87692 AU (430.381 Gm)
TJupiter	3.683
Physical characteristics
Dimensions	19.75±0.9 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	26.023 h (1.0843 d) [4]; 26.038 h [5]
Geometric albedo	0.2334±0.022
Temperature	~ 189 K
Spectral type	S
Absolute magnitude (H)	10.79

Medusa (minor planet designation: 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.[5]

References

"Discovery Circumstances: Numbered Minor Planets (1)-(5000)". IAU-Minor Planet Center. Retrieved 22 August 2016.
"Medusa". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005. (Subscription or UK public library membership required.)
"The Asteroid Orbital Elements Database". astorb. Lowell Observatory.
Yeomans, Donald K., "149 Medusa", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.
Pilcher, Frederick (April 2011), "Rotation Period Determinations for 25 Phocaea, 140 Siwa, 149 Medusa 186 Celuta, 475 Ocllo, 574 Reginhild, and 603 Timandra", The Minor Planet Bulletin, 38 (2), pp. 76–78, Bibcode:2011MPBu...38...76P.

External links

149 Medusa at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
149 Medusa at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters

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[MPC-disc-1] "Discovery Circumstances: Numbered Minor Planets (1)-(5000)". IAU-Minor Planet Center. Retrieved 22 August 2016.

[2] "Medusa". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005. (Subscription or UK public library membership required.)

[lowell-3] "The Asteroid Orbital Elements Database". astorb. Lowell Observatory.

[JPL-4] Yeomans, Donald K., "149 Medusa", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.

[Pilcher2011-5] Pilcher, Frederick (April 2011), "Rotation Period Determinations for 25 Phocaea, 140 Siwa, 149 Medusa 186 Celuta, 475 Ocllo, 574 Reginhild, and 603 Timandra", The Minor Planet Bulletin, 38 (2), pp. 76–78, Bibcode:2011MPBu...38...76P.