65 Cybele
65 Cybele is one of the largest asteroids in the Solar System, located in the outer part of the asteroid belt. It gives its name to the Cybele group of asteroids that orbit in a 2:1 resonance with Jupiter. It is an X-type, relatively dark asteroid that spins about once every 6.08 hours. It was discovered on 8 March 1861 by German astronomer Wilhelm Tempel at the Marseille Observatory in France and was named after Cybele, the earth goddess; there was a brief disagreement over the naming, but the name Cybele was kept.
Cybele is quite large, with estimated dimensions around 260–270 kilometers across (ranges from about 218 to 300 km in different measurements). It has a mass of about 1.5×10^19 kilograms and a density of about 1.55 g/cm^3, indicating a rocky, somewhat porous composition. Its shape is irregular, as shown by stellar occultations and infrared observations.
The orbit around the Sun takes about 6.3 years, with an average distance of roughly 3.43 AU. It has a modest orbital tilt of about 3.6 degrees and a small eccentricity, meaning its path around the Sun is a gentle ellipse.
65 Cybele is notable for its size and for helping define the Cybele group of outer-belt asteroids, and it continues to be studied to better understand the history of the early Solar System.
This page was last edited on 3 February 2026, at 16:03 (CET).