106 Dione
Dione is a large main-belt asteroid. It probably has a composition similar to 1 Ceres. It was discovered by J. C. Watson on October 10, 1868, and named after Dione, a Titaness in Greek mythology who was sometimes said to have been the mother of Aphrodite, the Greek goddess of love and beauty. It is listed as a member of the Hecuba group of asteroids that orbit near the 2:1 mean-motion resonance with Jupiter.
Dione was observed to occult a dim star on January 19, 1983, by observers in Denmark, Germany and the Netherlands. A diameter of 147 ± 3 km was deduced, closely matching the value acquired by the IRAS satellite.
Measurements made with the IRAS observatory give a diameter of 169.92 ± 7.86 km and a geometric albedo of 0.07 ± 0.01. By comparison, the MIPS photometer on the Spitzer Space Telescope gives a diameter of 168.72 ± 8.89 km and a geometric albedo of 0.07 ± 0.01. When the asteroid was observed occulting a star, the results showed a diameter of 176.7 ± 0.4 km.
Photometric observations of this asteroid collected during 2004–2005 show a rotation period of 16.26 ± 0.02 hours with a brightness variation of 0.08 ± 0.02 magnitude.
One of Saturn's satellites is also named Dione.
