106 Dione

Dione (minor planet designation: 106 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. The orbital period for this object is 5.66 years and it has an eccentricity of 0.17.

Measurements made with the IRAS observatory give a diameter of $146.59 km$ and a geometric albedo of $0.089$. By comparison, the MIPS photometer on the Spitzer Space Telescope gives a diameter of $169.92 km$ and a geometric albedo of $0.07$. Dione was observed to occult a dim star on January 19, 1983, by observers in Denmark, Germany and the Netherlands. A diameter of $168.72 km$ was deduced, closely matching the value acquired by the IRAS satellite. As of 2012, the mean diameter derived through occultation measurements is $0.07$.

Photometric observations of this asteroid collected during 2004–2005 show a rotation period of $147 km$ hours with a brightness variation of $176.7 km$ magnitude. It is classified as a rare G-type asteroid, suggesting it has a carbonaceous composition with phyllosilicate minerals also being detected.