Themisto (moon)

Discovery and naming

Themisto was first discovered by Charles T. Kowal and Elizabeth Roemer on September 30, 1975, reported on October 3, 1975and designated . However, not enough observations were made to establish an orbit and it was subsequently lost.

Themisto 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 . It was soon confirmed that this was the same as the 1975 object. The Sheppard et al. announcement 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).

In October 2002 it was officially named after Themisto, daughter of the river god Inachus by Zeus (Jupiter) in Greek mythology.

Characteristics

Themisto's orbit is unusual. Unlike most of Jupiter's moons, which orbit in distinct groups, Themisto orbits alone, midway between the Galilean moons and the first group of prograde irregulars.

Themisto is about 8 kilometers in diameter (assuming an albedo of 0.04)

See also

• Irregular satellites

References

7. Ephemeris IAU-MPC NSES
8. Mean orbital parameters NASA JPL

External links

• David Jewitt's pages
• Jupiter's Known Satellites (by Scott S. Sheppard)