Uranus

The Sideways Planet
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    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 ›

    Ten Things to Know About Uranus

    Ten Things to Know About Uranus

    1

    Huge

    Uranus is about four times wider than Earth. If Earth were a large apple, Uranus would be the size of a basketball.

    2

    Seventh Wanderer

    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).

    3

    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).

    4

    Ice Giant

    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.

    5

    Gassy

    Uranus has an atmosphere made mostly of molecular hydrogen and atomic helium, with a small amount of methane.

    6

    Many Moons

    Uranus has 27 known moons, and they are named after characters from the works of William Shakespeare and Alexander Pope.

    7

    The Other Ringed World

    Uranus has 13 known rings. The inner rings are narrow and dark and the outer rings are brightly colored.

    8

    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.

    9

    Lifeless

    Uranus cannot support life as we know it.

    10

    One cool fact

    Like Venus, Uranus rotates east to west. But Uranus is unique in that it rotates on its side.

    Did You Know?

    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.

    Pop Culture

    Pop Culture

    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.

    Build Your Own 3D Glasses

    Build Your Own 3D Glasses

    With a few materials and a few steps, you can build your own glasses to view 3D images.

    Resources

    Resources

    NASA SpacePlace: Uranus

    Uranus Lithograph - 2013 (PDF, 896 KB)

    NASA Planetary Photojournal - Uranus

    National Space Science Data Center Photo Gallery - Uranus

    Voyager 2 Science Summary for Uranus

    The Uranian Ring System

    NASA's Planetary Photojournal - Uranian Rings

    Power to Explore: Radioisotope Power

    Solar System News