NationMaster - Encyclopedia: 140 Siwa

**140 Siwa**
Orbital characteristics ^{1 (ftp://ftp.lowell.edu/pub/elgb/astorb.html)}
Orbit type	Main belt
Semimajor axis	2.732 AU
Perihelion distance	2.143 AU
Aphelion distance	3.322 AU
Orbital period	4.52 years
Inclination	3.19�
Eccentricity	0.216
Physical characteristics
Diameter ^{6 (http://nssdc.gsfc.nasa.gov/planetary/factsheet/asteroidfact.html)}	103 km
Mass ^{6 (http://nssdc.gsfc.nasa.gov/planetary/factsheet/asteroidfact.html)}	1.5 � 10¹⁸ kg
Rotation period	18.5 hours
Spectral class ^{5 (http://spiff.rit.edu/richmond/parallax/phot/LCSUMPUB.TXT)}	P (C ^{6 (http://nssdc.gsfc.nasa.gov/planetary/factsheet/asteroidfact.html)})
Abs. magnitude ^{1 (ftp://ftp.lowell.edu/pub/elgb/astorb.html)}	8.34
Albedo ^{4 (http://dorothy.as.arizona.edu/DSN/IRAS/index_iras.html)}	0.067
History ^{2 (http://cfa-www.harvard.edu/iau/lists/NumberedMPs.html)}
Discoverer	J. Palisa, 1874

140 Siwa is a large and dark main belt asteroid. It has a composition of a P (or possibly C-type) asteroid.

It was discovered by J. Palisa on October 13, 1874 and named after Siwa, the Slavic goddess of fertility.

Siwa has a very flat lightcurve, indicating a spherical body.

The Rosetta comet probe was to visit Siwa on its way to comet 46P/Wirtanen in July, 2008. However, the mission was rerouted to comet 67P/Churyumov-Gerasimenko and the flyby had to be abandoned.

Categories: Main Belt asteroids

Results from FactBites:

ESA - Rosetta - Debris of the Solar System: asteroids Otawara and Siwa (388 words)
	Siwa will be the largest asteroid ever encountered by a spacecraft, while (apart from a tiny asteroid moon called Dactyl) Otawara will be the smallest.
	Otawara is suspected to be a chunk of once-molten basalt (a type V or SV asteroid), and Siwa seems to be a carbon-rich object, which is fler than coal (a type C asteroid).
	At this time, Siwa will be about 470 million km from the Earth, so that signals from the spacecraft will take 26 minutes to reach ground stations.

More results at FactBites »

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