Because of its almost-perpendicular axis orientation, there is a debate over which of Uranus' poles is its north pole. This debates leads to yet another: Is Uranus spinning in a retrograde orbit (like Venus) or not (like the other planets)?

SIZE
Uranus is about 31,690 miles (51,118 km) in diameter. This is about 4 times the diameter of the Earth.

This gas giant is the third-largest planet in our Solar System (after Jupiter and Saturn).

MASS AND GRAVITY
Uranus' mass is about 8.68 x 10²⁵ kg. This is about 14 times the mass of the Earth. The gravity on Uranus is only 91% of the gravity on Earth. This is because it is such a large planet (and the gravitational force a planet exerts upon an object at the planet's surface is proportional to its mass and to the inverse of its radius squared).

A 100-pound person on Uranus would weigh 91 pounds.

LENGTH OF A DAY AND YEAR ON URANUS
Each day on Uranus takes 17.9 Earth hours. A year on Uranus takes 84.07 Earth years; it takes 84.07 Earth years for Uranus to orbit the sun once.

URANUS' ORBIT AND DISTANCE FROM THE SUN
Uranus is over 19 times as far from the Sun as the Earth is; it averages 19.18 A.U.

At aphelion (the farthest point in its solar orbit) it is 1,850,000,000 miles (3,003,000,000 km) from the Sun. At perihelion (the closest point in its solar orbit) it is 1,700,000,000 miles (2,739,000,000 km) from the Sun.

TEMPERATURE
The mean temperature on the surface of Uranus' cloud layer is -350°F (59 K). Uranus radiates very little heat in comparison with the other gas giants, Jupiter, Saturn and Neptune).

PLANETARY COMPOSITION AND ATMOSPHERE
Uranus is a frozen, gaseous planet with a molten core. Uranus' atmosphere consists of 83% hydrogen, 15% helium and 2% methane.

For more information on Uranus' composition, click here.

RINGS

Uranus and its rings photographed by an infrared camera. Uranus has a belt of 11 faint, narrow rings composed of rock and dust. They circle Uranus is very elliptical orbits. These rings are only a fraction of the size of Saturn's rings, and were only discovered in 1977. For more information on Uranus' rings, click here.

MOONS

Oberon, the largest moon of Uranus. Photo taken by NASA's Voyager mission in 1986.

Uranus has 5 large moons (2 were discovered by Wm. Herschel in 1781, 2 were discovered by Wm. Lassell in 1851, and one by G. Kuiper in 1948) and many small moons (which were discovered much later).

For more information on Uranus' moons, click here.

DISCOVERY OF URANUS
Uranus was discovered by the British astronomer William Herschel on March 13, 1781. Herschel also discovered two of the moons of Uranus (Titania and Oberon) and some of the moons of Saturn.

URANUS-EARTH COMPARISON

This is the symbol of the planet Uranus.

Find It!, a quiz on Uranus.

An interactive puzzle about Uranus

Uranus Cloze Printout: A fill-in-the-blanks activity on the planet Uranus. Answers