(pronunciation : YUR uh nus)

NASA, image by Voyager 2, 1986

Uranus is the seventh planet from the Sun and the third largest. It is a very cold planet because it is so far from the Sun. Uranus is one of the four gas giants in our solar system.

Uranus and its neighbour Neptune are also called "ice giants" because both planets differ from the gas giants Jupiter and Saturn. But Uranus is not a giant ball of ice. It has no solid surface. Its surface is thought to resemble an ocean of "slush", made of a mixture of water, ammonia and methane ices. There may be a rocky core at the centre of the planet.

Hubble Space Telescope 2006
Credit: NASA, ESA, L. Sromovsky and P. Fry (University of Wisconsin),
H. Hammel (Space Science Institute), and K. Rages (SETI Institute)

The planet is surrounded by thick clouds. The atmosphere is made up of gases (mainly hydrogen, some helium and a small amount of methane). The planet looks blue-green because of a gas called methane in its atmosphere.

As of 2005 scientists have found 13 rings around Uranus. (The rings are made up of particles up to 10 meters in diameter. )

Hubble Space Telescope 2003
Credit: NASA, ESA, and M. Showalter (SETI Institute)

An odd thing about this planet is that it spins on its side. Long ago a very large object may have smashed into Uranus and changed the direction of its spin. A day on Uranus is just over 17 hours (shorter than a day on Earth). It takes 84 Earth years to revolve around the Sun. One pole faces the sun continuously while the other pole faces away. Each pole gets about 42 years of continuous sunlight followed by 42 years of darkness.

Astronomers using the Hubble Space Telescope have found 27 moons. Some are tiny, while some are hidden within the rings.

On a very clear night Uranus can be seen from Earth without a telescope. Voyager 2 is the only spacecraft to have visited the planet (January, 1986).

Uranus was named after the Greek god of the sky.

"a computer image of the surface of Uranus, with the Voyager spacecraft seen in the sky above"

Uranus courtesy JPL

SPACE ARTWORK "Courtesy Jet Propulsion Laboratory. Copyright (c) California Institute of Technology, Pasadena, CA.
All rights reserved." site: http://samadhi.jpl.nasa.gov/art/


Large photo : Image of Uranus taken by Voyager 2
in late January 1986.(credit NASA, Voyager 2)
information from NASA Solar System Exploration

web page by J.Giannetta
updated April 2009