Solar System Exploration: Planet Selector: Uranus

PLANET SELECTOR

ABOUT URANUS

Uranus is the only giant planet whose equator is nearly at right angles to its orbit. A collision with an Earth-sized object may explain the unique tilt. Nearly a twin in size to Neptune, Uranus has more methane in its mainly hydrogen and helium atmosphere than Jupiter or Saturn. Methane gives Uranus its blue tint.
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Featured Mission: Voyager 2
Most of what we know about Uranus came from Voyager 2's flyby in 1986. The spacecraft discovered 10 additional moons and several rings before heading on to Neptune.
Read More About Voyager 2 >>

VITAL STATISTICS

Average Distance from Sun:	2,870,972,200 km (1,783,935,996 miles)
Diameter:	50,724 km (31,518 miles)
Volume:	63.1 x Earth's
Mass:	86,832,000,000,000,000,000,000,000 kg (14.536 x Earth's)
Length of Day:	17.24 Earth hours
Length of Year:	84.02 Earth years
Known Moons:	27

SIZE & DISTANCE

If the Sun was as tall as a typical front door, Earth would be the size of a nickel - and Uranus would be about as big as a baseball.

Average Distance from the Sun: 2,870,972,200 km (19.19 A.U.)

EXTREME SPACE

Say What?
Uranus is the only planet with a name sure to elicit giggles. The proper way to say the name is YOOR--un--nus. It was almost named 'Georgium Sidus' to honor an English king, but tradition prevailed and in 1850 the planet got its frequently mispronounced mythological name.

Sideswiped
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. Scientists think the tilt may be the result of a collision with a planet-sized object.

Is That Planet Flirting?
Uranus' rings were discovered by accident. Two teams set up to watch a bright star pass behind Uranus - a way to peek at the planet's atmosphere - were surprised when the star unexpectedly blinked out. Nine of Uranus's rings caused the star to wink at them as each ring in turn blocked the light of the star.

Shakespearian Satellites
Uranus' moons get their names from classic literature, not mythology. Among the moons orbiting Uranus, you will find Shakespeare's star-crossed lover Juliet of ''Romeo and Juliet'', unfortunate Ophelia from ''Hamlet'' and that mischievous fairy Puck from ''A Midsummer Night's Dream.

Quick Study
Only one spacecraft has visited distant Uranus. After traveling more than 3,000,000,000 km (1,800,000,000 miles) in nine years, NASA's Voyager 2 gathered much of its critical information about the mysterious planet in a scant six hours.

Long Distance Upgrade
Think upgrading software your computer is a pain? Try doing it from billions of kilometers away. Voyager 2's mission controllers pulled off a long- distance upgrade in 1986 to enable the spacecraft to send back sharp pictures taken at high speed in faint sunlight - only 1/400th of the light we see on Earth.

TIMELINE

1781 - English Astronomer William Herschel discovers Uranus. It is the first planet discovered with the aid of a telescope.

1787-1851 - Four Uranian moons - Titania, Oberon, Ariel and Umbriel - are discovered.

1948 - Dutch astronomer Gerald Kuiper discovers Uranian moon Miranda.

1977 - Two teams unexpectedly discover Uranus' ring system while watching a star pass behind the planet.

1986 - NASA's Voyager 2 becomes the first - and so far the only - spacecraft to visit Uranus, discovering 10 additional moons and several rings as it flies past.

1997-now - Astronomers discover more tiny moons orbiting Uranus. In 2005, NASA's Hubble Space Telescope photographed a new pair of rings around Uranus.

SLIDE SHOW

Uranus and Moons (False Color)
Another View of Uranus and Moons
Near-Infrared Uranus and Moons
Uranus in True and False Color
Uranus' Atmosphere
Uranus' Moon Ariel
Varied Terrain on Miranda
Miranda in Detail
Uranus' Ring System
Leaving Uranus

MOONS

There are 27 known moons orbiting Uranus. There are probably more out there, but it's very difficult to spot the small, dark objects at such an extreme distance. Ten of the moons were discovered when Voyager 2 flew past in 1986. Miranda is the strangest Uranian moon. Miranda's chaotic jumble of terrain - photographed by Voyager 2 - is unparalleled elsewhere in the solar system and remains largely unexplained.