Mneme (moon)

Mneme /ˈnm/, 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.[3][4]

Mneme Discovery Image.jpg
Discovery image of Mneme (centered) from February 2003
Discovered byBrett J. Gladman et al.
Scott S. Sheppard et al.
Discovery date9 February 2003
Jupiter XL
Named after
Μνήμη Mnēmē
S/2003 J 21
AdjectivesMnemean /nɛˈmən/
Orbital characteristics[2]
21069000 km
−620.0 days
Satellite ofJupiter
GroupAnanke group
Physical characteristics
Mean diameter
2 km

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.[5] 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°.


  1. ^ "Mneme". Unabridged (Online). n.d.
  2. ^ S.S. Sheppard (2019), Moons of Jupiter, Carnegie Science, on line
  3. ^ IAUC 8138: S/2003 J 21 2003 May 30 (discovery)
  4. ^ MPEC 2003-K45: S/2003 J 21 2003 May 29 (discovery and ephemeris)
  5. ^ IAUC 8502: Satellites of Jupiter 2005 March 30 (naming the moon)