URANUS WAS THE FIRST PLANET to be discovered since the use of the telescope. It was discovered by accident, when William Herschet observing from Bath, England, set about remeasuring all the major stars with his 6-in (15-cm) reflector telescope (p.24). In 1781 he noticed an unusually bright object in the zodiacal constellation of Gemini. At first he assumed it was a nebula (pp.60-61) and then a comet (pp.58-59), but it moved in a peculiar way. The name of Uranus was suggested by the German astronomer Johann Bode, who proposed that the planet be named after the father of Saturn, in line with established classical traditions. Bode is also famous as the creator of Bode's law-a mathematical formula that predicted roughly where planets should lie.

Uranus spins on an axis that is tilted at an angle of nearly 98° from the plane of its orbit. This means that, compared with all the other planets in the solar system, Uranus is spinning on its side. During its 84-year orbit of the Sun, the north pole of Uranus will have 42 years of continuous, sunny summer, while the south pole has the same length of sunless winter, before they swap seasons. This odd tilt may be the result of a catastrophic collision during the formation of the solar system.

LITERARY MOONS: All the satellites of Uranus are named after sprites and spirits drawn from English literature. The American astronomer Gerard P Kuiper (1905-1973) discovered Miranda in 1948. (Miranda and Ariel are characters from William Shakespeare's The Tempest.) It has a landscape unlike any other in the solar system. Miranda seems to be composed of a jumble of large blocks. Scientists have suggested that these were caused by some huge impact during which Miranda was literally blown apart. The pieces drifted back together through gravitational attraction, forming this strange mixture of rock and ice.

URANUS RING SYSTEM: While watching the occultation of Uranus in 1977, astronomers noticed that the faint star "blinked on and off" several times at the beginning and end of the occultation. They concluded that Uranus must have a series of faint rings that caused the star to"blink"by blocking off its light as it passed behind them. The Voyager 2 flyby in 1986 uncovered two more rings. The rings of Uranus are thin and dark, made up of particles only about a yard (1 m) across. The broad bands of dust between each ring suggest that the rings are slowly eroding.