Uranus is the seventh planet from the Sun and is unique for its extreme tilt. Unlike other planets, Uranus is tilted on its side at an angle of about 98 degrees, meaning it essentially rolls around the Sun like a ball. This strange tilt causes extreme seasons, with each pole experiencing 42 years of continuous sunlight or darkness. The planet is composed mainly of hydrogen, helium, and methane, and its atmosphere gives it a blue-green color. Uranus is a gas giant, but unlike Jupiter and Saturn, it is often classified as an "ice giant" because it contains more ice and less hydrogen and helium. Uranus has a system of rings and 27 known moons.