IntroductionThe seventh planet from the sun with the third largest diameter in our solar system, Uranus is very cold and windy. The ice giant is surrounded by 13 faint rings and 27 small moons as it rotates at a nearly 90-degree angle from the plane of its orbit. This unique tilt makes Uranus appear to spin on its side, orbiting the sun like a rolling ball.
The first planet found with the aid of a telescope, Uranus was discovered in 1781 by astronomer William Herschel, although he originally thought it was either a comet or a star. It was two years later that the object was universally accepted as a new planet, in part because of observations by astronomer Johann Elert Bode.
William Herschel tried unsuccessfully to name his discovery Georgium Sidus after King George III. Instead the planet was named for Uranus, the Greek god of the sky, as suggested by Johann Bode. Expore Uranus ›
Uranus is about four times wider than Earth. If Earth were a large apple, Uranus would be the size of a basketball.
Uranus orbits our Sun, a star, and is the seventh planet from the Sun at a distance of about 1.8 billion miles (2.9 billion kilometers).
Short-ish Day, Longish Year
Uranus takes about 17 hours to rotate once (a Uranian day), and about 84 Earth years to complete an orbit of the Sun (a Uranian year).
Uranus is an ice giant. Most of its mass is a hot, dense fluid of "icy" materials – water, methane and ammonia – above a small rocky core.
Uranus has an atmosphere made mostly of molecular hydrogen and atomic helium, with a small amount of methane.
Uranus has 27 known moons, and they are named after characters from the works of William Shakespeare and Alexander Pope.
The Other Ringed World
Uranus has 13 known rings. The inner rings are narrow and dark and the outer rings are brightly colored.
A Bit Lonely
Voyager 2 is the only spacecraft to fly by Uranus. No spacecraft has orbited this distant planet to study it at length and up close.
Uranus cannot support life as we know it.
One cool fact
Like Venus, Uranus rotates east to west. But Uranus is unique in that it rotates on its side.
Did You Know?
Uranus' unique sideways rotation makes for weird seasons. The planet's north pole experiences 21 years of nighttime in winter, 21 years of daytime in summer and 42 years of day and night in the spring and fall.
Uranus is the "butt" of more than a few jokes and witty (and not so witty) puns, but it's also a frequent destination in various fictional stories, such as the video game Mass Effect and TV shows like Doctor Who. The radioactive element uranium was named after Uranus when it was discovered in 1789, just eight years after the planet was discovered.
Uranus Lithograph - 2013 (PDF, 896 KB)