Titan is Saturn's largest moon and the second largest moon in the solar system. It was discovered by Dutch astronomer Christiaan Huygens in 1655 and remains the only natural satellite in the solar system known to have a significant atmosphere. The thick, opaque atmosphere obscures the surface, but some surface detail has been observed via the Hubble Space Telescope. When the Cassini-Huygens spacecraft arrived on Saturn in 2004, it revealed that Titan's surface has what in common with Earth? Discuss (http://forum.thefreedictionary.com/postst55725_Saturn-s-Largest-Moon-Is-Discovered--1655-.aspx)