Metis (moon)

Metis

Image taken by Galileo's Solid State Imager between November 1996 and June 1997
Discovery
Discovered by	S. Synnott
Discovery date	4 March 1979
Designations
Pronunciation	/ˈmiːtəs/[1]
Named after	Μήτις Mētis
Adjectives	Metidian, Metidean /mɛˈtɪdiən/
Orbital characteristics
Periapsis	127974 km[a]
Apoapsis	128026 km[a]
Mean orbit radius	128000 km (1.792 RJ)[2][3]
Eccentricity	0.0002[2][3]
Orbital period (sidereal)	0.294780 d (7 h, 4.5 min)[2][3]
Average orbital speed	31.501 km/s[a]
Inclination	0.06° (to Jupiter's equator)[2][3]
Satellite of	Jupiter
Physical characteristics[4]
Dimensions	60 km × 40 km × 34 km
Mean radius	21.5±2.0 km
Surface area	≈ 6200 km2[a]
Volume	≈ 42700 km3[a]
Mass	≥6.4×1016 kg[a]
Mean density	≥1.5 g/cm3
Surface gravity	≥0.8 cm/s2 (average)
Synodic rotation period	synchronous
Axial tilt	zero
Albedo	0.061±0.003[5]
Temperature	≈ 123 K

Metis /ˈmiːtəs/, also known as Jupiter XVI, is the innermost known moon of Jupiter. It was discovered in 1979 in images taken by Voyager 1, and was named in 1983 after the first wife of Zeus, Metis. Additional observations made between early 1996 and September 2003 by the Galileo spacecraft allowed its surface to be imaged.

Metis is tidally locked to Jupiter, and its shape is strongly asymmetrical, with the largest diameter being almost twice as large as the smallest one. It is also one of the two moons known to orbit Jupiter in less than the length of Jupiter's day, the other being Adrastea. It orbits within the main ring of Jupiter, and is thought to be a major contributor of ring material.

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