Facts About Uranus, the Sideways Planet

What kind of planet is Uranus?

Uranus is the seventh planet from the Sun and the third largest. NASA calls it an ice giant: very cold and windy, about four times wider than Earth. If Earth were the size of a nickel, Uranus would be about as big as a softball.

Uranus was the first planet discovered with a telescope. The astronomer William Herschel spotted it in 1781 and at first thought it was a comet or a star. Herschel wanted to name it after King George III, but it was eventually named, at the suggestion of astronomer Johann Bode, for Uranus, the Greek god of the sky.

Uranus by the numbers

Source: NASA Planetary Fact Sheet and NASA Science.

Sunlight takes about 2 hours and 40 minutes to reach Uranus. A person who is 84 years old on Earth would have lived for just one year on Uranus.

The planet that rolls on its side

Uranus's axis is tilted about 98 degrees, so it spins on its side, rolling around the Sun like a ball. No other planet does this. Like Venus, it also spins backward compared with most planets.

Scientists aren't sure what tipped it over. NASA says one leading idea is a collision with an Earth-sized object long ago.

The tilt gives Uranus the most extreme seasons in the solar system. For about a quarter of its 84-year orbit, one pole points almost straight at the Sun, while the other half of the planet has a dark winter lasting about 21 years. Then the seasons slowly swap.

In the 3D view, turn on "Axis and equator" to see the tilt: Uranus's equator, rings and moons all circle it nearly up and down compared with its path around the Sun.

An ice giant: what's inside Uranus?

"Ice giant" doesn't mean Uranus is a frozen ball. Tap the cutaway in the diagram:

1. Atmosphere: mostly hydrogen and helium, with some methane and traces of water and ammonia. Methane absorbs red light, which is why Uranus looks blue-green.
2. Icy mantle: NASA says at least 80 percent of Uranus's mass is a hot, dense fluid of "icy" materials, water, methane and ammonia. Scientists call these ices even though they're not solid.
3. Rocky core: a small core of rock at the center, where NASA estimates temperatures reach about 4,982 °C (9,000 °F).

Uranus has no solid surface. Its winds blow up to about 900 kilometers per hour.

Even though its insides are hot, Uranus gives off surprisingly little heat. Its upper atmosphere has the coldest temperature measured on any planet: about −224 °C.

Rings and moons

Uranus has 13 faint rings, made of dark particles that are hard to see. From closest to farthest, NASA lists them as Zeta, 6, 5, 4, Alpha, Beta, Eta, Gamma, Delta, Lambda, Epsilon, Nu and Mu. Because Uranus is tipped, its rings stand almost upright compared with its orbit.

NASA counts 29 moons as of August 2026, the newest found in 2025 with the James Webb Space Telescope. Most planets' moons are named after myths, but Uranus's are named after characters in plays and poems by William Shakespeare and Alexander Pope. The five biggest are:

Missions to Uranus

Only one spacecraft has ever visited Uranus. NASA's Voyager 2 flew past in January 1986 and discovered 10 new moons and two new rings. Since then, the Hubble Space Telescope, the James Webb Space Telescope and big telescopes on Earth have watched its clouds and seasons change. In 2022, a major report by U.S. scientists recommended a Uranus orbiter and probe as NASA's next big planetary mission.

How far away is Uranus?

Uranus orbits about 19 times farther from the Sun than Earth does, and about twice as far out as Saturn. That huge distance is why it took so long to discover, and why it's so hard to visit: Voyager 2, launched in 1977, needed more than eight years to get there. From Uranus, the Sun would look like a very bright star rather than a big glowing disk. In the 3D solar system, switch distances to "To scale" and zoom out to see how far beyond Saturn it really is.

Fun facts about Uranus

• Uranus is wider than Neptune but has less mass; after Saturn, it's the second least dense planet.
• If you weigh 80 pounds on Earth, you'd weigh about 71 pounds at Uranus's cloud tops.
• Uranus's magnetic field is tipped nearly 60 degrees from its spin axis, and its auroras don't line up with its poles.
• Uranus's magnetic tail is twisted into a long corkscrew shape by the planet's sideways spin.

Learning about Uranus at home

Push a pencil through a foam ball, tilt it on its side, and walk it in a circle around a lamp: kids will see how one pole faces the Sun for half the trip and the other pole for the other half. Take the facts quiz above and print the labeled Uranus diagram.

Next, compare Uranus with its twin, Neptune, and with ringed Saturn, or see it orbit in the 3D solar system.