This disc of Uranus, photographed by Voyager 2.
Credit JPL/Galaxy

Amazing fact!

Uranus was the first planet ever to be ‘discovered’ when it was found by William Herschel in 1781 (Mercury, Venus, Mars, Jupiter and Saturn are all visible to the naked eye and had been known about since people first started looking to the stars thousands of years ago).

About Uranus

Now we have reached the realm of the ice giants. Uranus – the seventh planet from the Sun – is 51,120 kilometres across, and 14 times the mass of Earth. Uranus is 2.88 billion kilometres from the Sun and is very cold. Not as much is known about Uranus as is known about Jupiter and Saturn – only one spacecraft has ever visited it, and that was Voyager 2 in 1986, which quickly flew past before moving on to Neptune.

Uranus’ atmosphere is fairly bland, though it does have some small storms. More intriguingly, Uranus has somehow been knocked onto its side, possibly by a collision with another planet or a moon. So when Uranus’ south pole is pointed towards the Sun, the north pole is in darkness, and vice versa. Uranus also has 13 rings.

Uranus has 27 known moons, and perhaps the most interesting in Miranda (its moons are named after characters in William Shakespeare’s plays; Miranda was the heroine in ‘The Tempest’). Miranda is a patchwork quilt of a moon, and looks like it has been smashed up (or perhaps melted) and then put back together again.

Miranda and rings
Miranda from Voyager, left, and Uranus from the Hubble Space Telescope. Credit: NASA

Click on each of the images below to find out more about that Solar System object!