1. Third largest planet in the solar system by diameter and least massive of the gas giants. Discovered by Sir
William Herschel in 1781. A naked eye object in good conditions if you know where and what to look for. Higher proportions of water
ice, methane and ammonia in the atmospheres of Uranus and Neptune have led astronomers to class these worlds in a separate category known as the
ice giants. Knocked on its side by an early impact to its current 98-degree axial tilt, Uranus rolls almost
like a ball along its orbit, with first one hemisphere and then the other experiencing daylight. Uranus is known for a system of dark rings of carbonaceous material. Orbits the
sun at 1.787 billion miles mean distance, or approaching twenty times
Earth's distance, from the
Sun. Wins the booby prize for the least photogenic planet in the system, appearing a more or less featureless cyan globe, though this
may change at the equinoxes every 42
Earth years. Visited by Voyager 2 in 1986. At last count, 27 moons.
2. Romanised form of the Greek god's name Ouranos, god of the heavens.
3. No scatological jokes, please.
