THEMISTO (MOON)

'Themisto' ''(thə-mis'-toe,'' ; Greek ''Θεμιστώ),'' or 'Jupiter XVIII', is a prograde irregular satellite of Jupiter. It was first discovered by Charles T. Kowal and Elizabeth Roemer on September 30, 1975, reported on October 3, 1975^[3]and designated 'S/1975 J 1', but not enough observations were made to establish an orbit and it was subsequently lost.
It appeared as a footnote in astronomy textbooks into the 1980s. Then, in 2000, a seemingly new satellite was discovered by Scott S. Sheppard, David C. Jewitt, Yanga R. Fernández and Eugene A. Magnier, and was designated 'S/2000 J 1'. It was soon confirmed that this was the same as the 1975 object. The Sheppard et al. announcement^[4] was immediately correlated with an August 6 2000 observation by the team of Brett J. Gladman, John J. Kavelaars, Jean-Marc Petit, Hans Scholl, Matthew J. Holman, Brian G. Marsden, Philip D. Nicholson and Joseph A. Burns — an observation that was reported to the Minor Planet Center but not published as an IAU Circular (IAUC).^[5]
In October 2002 it was officially named after Themisto^[6], daughter of the river god Inachus, mother of Ister (the river Danube) by Zeus (Jupiter) in Greek mythology.

Themisto's orbit is unusual, as it orbits about midway between the Galilean moons and the first group of prograde irregulars. The diagram illustrates its orbit in relation to other irregular satellites of Jupiter. The satellites above the horizontal axis are prograde, the satellites beneath it are retrograde. The yellow segments extend from the pericentre to the apocentre, showing the eccentricity.
Themisto is about 8 kilometers in diameter (assuming an albedo of 0.04)

Contents

See also

References

External links

See also

★ Irregular satellites

References

1. Sheppard, S. S.; Jewitt, D. C.; ''An abundant population of small irregular satellites around Jupiter'', Nature, '423' (May 2003), pp. 261-263
2. Physical parameters from JPL
3. IAUC 2845: ''Probable New Satellite of Jupiter'' 1975 October 3 (discovery)
4. IAUC 7525: ''S/1975 J 1 = S/2000 J 1'' 2000 November 25 (recovery)
5. MPEC 2000-Y16: ''S/1975 J 1 = S/2000 J 1, S/1999 J 1'' 2000 December 19 (recovery and ephemeris)
6. IAUC 7998: ''Satellites of Jupiter'' 2002 October 22 (naming the moon)

#

Ephemeris IAU-MPC NSES
#Mean orbital parameters NASA JPL

External links

★ David Jewitt's pages

★ Scott Sheppard's pages


''... | Callisto | 'Themisto' | Leda | ...''