1781: William Herschel discovers the planet Uranus.

Herschel, a German-born astronomer who moved to England as a young man, was not the first person to observe the seventh planet from the sun, but he was the first to correctly identify it as a planet. Prior to Herschel, Uranus was believed to be a star.

The ancients were aware of the six planets closest to the sun; Uranus was the first planet discovered that had been previously unknown.

Herschel originally christened his discovery Georgium Sidus ("George's Star") in honor of Britain's King George III and, in fact, a host of names were proposed before Uranus finally won out.

Uranus was originally believed to have five moons; at last count at least 27 satellites have been identified and named (for characters from the works of Shakespeare and Alexander Pope). The planet itself is composed largely of hydrogen, helium and methane, with a rock and ice core. It also has a ring system (discovered in 1977), albeit much fainter than the one girdling Saturn.