Introduction

Uranus is the seventh planet of our solar system, and was at one point thought to be quite bland compared to the rest of the gas giants, but this opinion is currently being revised. Its rotational axis is an exceptional feature, as most planets' axes are perpendicular to the ecliptic plane (the plane on which the planets lie, approximately, at all times). However, the axis of Uranus is at 90 degrees to the plane, and its magnetic field is inclined at 60 degrees to its rotation axis and offset from the centre of the planet. Despite this, its equatorial regions are still hotter than its poles, and the mechanism for this is as yet unexplained. The bulk of Uranus is a liquid core composed of water, ammonia and methane, and the planet has been observed in recent years to experience dramatic storms, with cloud speeds of up to 500 km per hour.

The infrared image of Uranus shows the clouds as bright orange patches (courtesy of NASA).

Rings and Moons

Like the rest of the gas giants, Uranus has a ring system. More visible than those on Neptune and Jupiter, Uranus' rings have been photographed by the Hubble Space Telescope, currently in orbit around earth, and this image, courtesy of NASA, shows them quite clearly. Uranus also has several moons. Twenty-seven are known at present, ten of those having been discovered on the Voyager 2 fly-by of 1986, and including some very tiny moons in a crowded region between the rings. Miranda, named for Shakespeare's heroine, is particularly fascinating due to its deep canyons and the wide age range of its visible surfaces.