Astronomy:Mneme (moon)

Mneme

Discovery image of Mneme (centered) from February 2003
Discovery
Discovered by	Brett J. Gladman et al. Scott S. Sheppard et al.
Discovery date	9 February 2003
Designations
Designation	Jupiter XL
Pronunciation	/ˈniːmiː/
Named after	Μνήμη Mnēmē
Alternative names	S/2003 J 21
Adjectives	Mnemean /nɛˈmiːən/
Orbital characteristics
Semi-major axis	21069000 km
Eccentricity	0.227
Orbital period	−620.0 days
Mean anomaly	338.9°
Inclination	148.6°
Longitude of ascending node	18.1°
|{{{apsis}}}|helion}}	41.7°
Satellite of	Jupiter
Group	Ananke group
Physical characteristics
Mean diameter	2 km
Apparent magnitude	23.3

Mneme /ˈniːmiː/, also known as Jupiter XL, is a retrograde irregular satellite of Jupiter. It was discovered by teams of astronomers led by Brett J. Gladman and Scott S. Sheppard in 2003, and was provisionally designated S/2003 J 21.

Mneme is about 2 kilometres in diameter, and orbits Jupiter at an average distance of 21,427,000 kilometres in 640.769 days, at an inclination of 149° to the ecliptic (148° to Jupiter's equator) with an eccentricity of 0.2214. Its average orbital speed is 2.43 km/s.

It was named in March 2005 after Mneme, one of the three original Muses. She is sometimes confused with Mnemosyne, mother of the Muses (the three or the nine, depending on the author) by Zeus (Jupiter).

Mneme belongs to the Ananke group, retrograde irregular moons which orbit Jupiter between 19.3 and 22.7 million kilometres, at inclinations of roughly 150°.