Since 1965, over 40 people have explored Mars through rovers and spacecraft. Jupiter has the Great Red Spot, a massive storm. Saturn's rings are made of ice. The Moon is rocky from volcanoes and was first walked on by humans in 1969. Earth is unique for its liquid water and life. Uranus has faint, fast clouds while Mercury is closest to the Sun but not hottest. Venus is rocky, Neptune icy, and Pluto is now classified as a dwarf planet due to its small size and orbit.