9 Metis

Discovery
Discoverer	Andrew Graham
Discovery Date	April 25, 1848
Alternate Designations	1974 QU2
Category	Main belt
Orbital Elements Epoch July 14, 2004 (JD 2453200.5)
Eccentricity (e)	0.122
Semi-Major Axis (a)	357.052 Gm (2.387 AU)
Perihelion (q)	313.556 Gm (2.096 AU)
Aphelion (Q)	400.548 Gm (2.678 AU)
Orbital Period (P)	1346.815 d (3.69 a)
Mean Orbital Speed	19.28 km/s
Inclination (i)	5.576°
Longitude of the Ascending Node (Ω)	68.982°
Argument of Perihelion (ω)	5.489°
Mean Anomaly (M)	274.183°
Physical Characteristics
Dimensions	235×165 km [1] (http://web.media.mit.edu/~win/hstpub.pdf) km
Mass	4.6×1018 kg
Density	2 ? g/cm³
Surface Gravity	0.036 m/s²
Escape Velocity	0.081 km/s
Rotation Period	0.2116 d 2 (http://www.psi.edu/pds/archive/lc.html)
Spectral Class	S-type asteroid 3 (http://spiff.rit.edu/richmond/parallax/phot/LCSUMPUB.TXT)
Absolute Magnitude	6.28
Albedo	0.160 3 (http://spiff.rit.edu/richmond/parallax/phot/LCSUMPUB.TXT)
Mean Surface Temperature	~244 K

9 Metis ("MEE tiss") is one of the largest Main belt asteroids. It is composed of silicates and metallic nickel-iron.

Metis was discovered by A. Graham on April 25, 1848; his only asteroid discovery. It is also the only asteroid to have been discovered from Ireland. Its name comes from the mythological Metis, a Titaness, daughter of Tethys and Oceanus (and thus an Oceanid), who was the first wife of Zeus and the mother of Athena. Zeus devoured her lest she bear a child more powerful than he.

Light curve data on Metis led to an assumption that it could have a satellite. However, subsequent observations failed to confirm this. [2] (http://www.bdl.fr/observateur/binast/binary_ast.php) [3] (http://www.johnstonsarchive.net/astro/asteroidmoonsq.html) Metis was later observed with the Hubble Space Telescope in 1993, which was able to resolve the irregular shape of the asteroid, but no satellites were detected. [4] (http://web.media.mit.edu/~win/hstpub.pdf)

Metis has been observed occulting a star no less than 5 times.

Metis is also the name of a satellite of Jupiter.

External links

• "Notice of discovery of Metis", MNRAS 8 (1848) 146 (http://adsabs.harvard.edu//full/seri/MNRAS/0008//0000146.000.html)
• Irish Astronomical History: Markree Castle Observatory and The Discovery of the Asteroid Metis (http://www.eaas.co.uk/news/metis.html)

The Minor Planets

Vulcanoids | Main belt | Groups and Families | Near-Earth objects | Jupiter Trojans

Centaurs | Trans-Neptunians | Damocloids | Comets | Kuiper Belt | Oort Cloud

(For other objects and regions, see: Binary asteroids, Asteroid moons and the Solar system)

(For a complete listing, see: List of asteroids)

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