Iapetus (pronounced /aɪˈæpɨtəs/, or as Greek Ιαπετός), occasionally Japetus (pronounced /ˈdʒæpɨtəs/), is the third-largest moon of Saturn, and eleventh in the solar system, discovered by Giovanni Domenico Cassini in 1671. Iapetus is best known for its dramatic 'two-tone' coloration, but recent discoveries by the Cassini mission have revealed several other unusual physical characteristics, such as an equatorial ridge that runs about halfway around the moon.