The seventh planet in the Solar System is Uranus. It was discovered by William Herschel, an English astronomer and composer, in March 1781 using a home-made telescope. The planet is named after the Greek god, Uranus, who, in mythology, ruled the heavens. The planet is the third largest in the Solar System with a diameter (width) of 51,118 kilometres (31,763 miles). It takes just over 84 years on Earth for Uranus to orbit the Sun. This is because the planet is so far away from the Sun (2,869,328,000 kilometres /1,740,200,000 miles away) meaning it has a greater distance to travel, and moves at such a slow speed because of the Sun's weaker pull of gravity.
Uranus is just about visible from Earth without a telescope as a very faint star. Even close up, the Voyager 2 spacecraft, which had already visited Jupiter and Saturn and would later visit Neptune, revealed little about the planet. It was simply a gigantic pale blue ball of hydrogen, helium and methane gas (methane filters out red light, so the planet appears blue). The planet is about a third of the size of Jupiter. It is possible that the planet has a small rocky core, surrounded by oceans of ice and water, with a windy sky above it. Wind speeds have been measured at 40 to 160 metres a second. Uranus also has a ring system, although these are the faintest in the Solar System. The picture below shows the rings (using images taken by Voyager 2), although the colour is not the natural colour, which would be as dark as charcoal.
The one difference between Uranus and the other planets in the Solar System is that it rotates on its side. It appears to roll around the Sun like a barrel. For more information about Uranus' tilt, click here. Uranus has at least 27 known moons which. Almost all of them are named after characters in Shakespeare's plays. 10 of these moons were discovered in 1985 and 1986 by the Voyager 2 spacecraft. Two of the other moon's (Titania and Oberon) were discovered by the planet's discoverer, William Herschel, in 1787. Ariel and Umbriel were discovered in 1851 by William Lassell, and Miranda was discovered in 1948 by Gerard Kuiper.