Uranus is the seventh planet from the Sun. It was discovered by William Herschel in 1781.
Uranus is a giant world, the third largest planet in our Solar System. 64 Earths would fit inside it. Despite its size, it spins rapidly. A day on Uranus lasts only 17 hours 14 minutes.
Uranus spins like a top knocked over on its side. This means that the Sun is sometimes directly overhead at the poles. Each pole has a summer and a winter lasting 21 years, making them the hottest and coldest places on the planet!
When the Voyager 2 spacecraft visited Uranus in 1986, hardly any clouds were visible. However, recent images by the Hubble Space Telescope have shown some very large storms.
The main gases in its thick atmosphere are hydrogen and helium, with a small amount of methane. (The methane scatters blue light, which is why Uranus appears blue). However, it is very different from Jupiter and Saturn.
Uranus is mainly made of ‘ices’ – a mixture of water, methane and ammonia. At its centre there may be a small rocky core. This means that it is very lightweight for its size.
Uranus has 27 known moons. None of these are very big. The largest satellites are Oberon and Titania, both more than 1,500 km in diameter.
Uranus also has at least a dozen dark, dusty rings. Most of these are extremely thin. They are kept in shape by nearby “shepherd” moons. At least one ring is created by meteorites crashing into a small satellite.
Uranus is the seventh planet from the sun in our solar system. This huge, ice giant is covered with clouds and is encircled by a belt of 11 rings and 22 known moons. Uranus' blue color is caused by the methane (CH4) in its atmosphere; this molecule absorbs red light.
Uranus' rotational axis is strongly tilted on its side (97.9°). Instead of rotating with its axis roughly perpendicular to the plane of its orbit (like all the other planets in our Solar System), Uranus rotates on its side (along its orbital path). This tipped rotational axis gives rise to extreme seasons on Uranus. For more information on Uranus' extreme seasons, click here.
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)?
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).
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.
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 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.
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).
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.
For more information on Uranus' rings, click here.
Oberon, the largest moon of Uranus. Photo taken by NASA's Voyager mission in 1986.
For more information on Uranus' moons, click here.
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.
This is the symbol of the planet Uranus.
Uranus has been visited by NASA's Voyager 2, whose closest approach was on January 24, 1986.
Uranus coloring page
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
How to write a report on a planet - plus a rubric.