The Eos family is a family of asteroids, first detected by the Japanese astronomer Kiyotsugu Hirayama (1874–1943) in 1918, that moves in the outer asteroid belt at a mean distance of 3.02 astronomical units from the Sun. Most Eos asteroids appear to belong class C (carbonaceous) or S (silicaceous); spectral studies have linked some Eos family members specifically with carbonaceous chondrites of the CO and CV type, while others have yet to be matched with known meteorite counterparts. This compositional variation suggests that the Eos parent body was partially differentiated. The family is named after 221 Eos, discovered on 18 January 1882 by Johann Palisa.