The Bright Blue Planet-Shaped Disc

How a disgruntled composer discovered a planet

This article belongs to the Hundred-Word Histories series.

Photo: NASA

When William Herschel peered into his homemade telescope on another March night in 1781, he was looking for double stars. Instead he found a bright blue disc and thought it was a comet or the side of a galaxy. At this point Herschel was just a disgruntled composer who had deserted the military band to study astronomy and search for stars. The ancients knew Mars and Venus and Jupiter and Saturn and Mercury, but Herschel had found the first planet invisible to the naked eye. It was named Uranus, father of Saturn, and Herschel went back to searching for stars.