Uranus is the seventh planet from the Sun. Its name is a reference to Uranus, the Greek god of the sky, who was the great-grandfather of Ares, grandfather of Zeus, and father of Cronus, according to Greek mythology. It possesses the Solar System's third-largest planetary radius and fourth-largest planetary mass. Uranus and Neptune are chemically similar, although their bulk chemical compositions vary from those of Jupiter and Saturn, the bigger gas giants. As a result, Uranus and Neptune are often referred to as "ice giants" to differentiate them from the other large planets.
Uranus, like the other classical planets, is visible to the naked eye, but due to its dimness and slow orbit, it was never identified as a planet by ancient observers. On March 13, 1781, Sir William Herschel made the first observation of Uranus, which led to its identification as a planet, extending the Solar System's recognized limits for the first time in history and making Uranus the first planet designated as such using a telescope.
Uranus features a ring system, a magnetosphere, and multiple moons, much like the other major planets. Because its axis of spin is slanted sideways, almost into the plane of its solar orbit, the Uranian system has a peculiar configuration. As a result, its north and south poles are located where the equators of most other planets are located. In 1986, photographs from the Voyager 2 spacecraft revealed Uranus to be a nearly featureless planet in visible light, lacking the cloud bands and storms seen on other big planets. The only spaceship to visit the planet is Voyager 2. As Uranus reached its equinox in 2007, observations from Earth revealed seasonal changes and increasing weather activity.
