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| | Space on Mar 13, 2014

This date in science: Uranus discovered, completely by accident

William Herschel noticed while surveying stars that one object moved apart from the star background. It was the first planet discovered since ancient times.

March 13, 1781. The 7th planet – Uranus – was discovered on this date, completely by accident. British astronomer William Herschel was performing a survey of all the stars that were of magnitude 8 – in other words, too faint to see with the eye – or brighter. That’s when he noticed an object that moved in front of the star background over time, clearly demonstrating it was closer to us than the distant stars. He surmised this object was orbiting the sun and that it was a new planet – the first discovered since ancient times.

Later, it turned out, astronomers learned they had observed Uranus as far back as 1690. But it was Herschel who first realized the true nature of this distant light in our sky.

Voyager 2 gave us our first close-up image of the planet Uranus in 1986.  Its images showed a featureless gas giant world.

Voyager 2 gave us our first close-up image of the planet Uranus in 1986. Its images showed a featureless gas giant world.

Voyager 2 image showing Uranus in true and false color. Image via NASA

Herschel proposed to name the object after King George III, but those outside of Britain weren’t pleased with the idea. Instead, on the suggestion of astronomer Johann Elert Bode, astronomers decided to follow the convention of naming planets for the ancient gods. Uranus – an ancient sky god, and one of the earliest gods in Greek mythology – was sometimes called Father Sky and was considered to be the son and husband of Gaia, or Mother Earth.

The closest humans ever got to the planet was in 1986, when the Voyager 2 spacecraft swung by the planet.

Today, Uranus is known to possess a complicated ring system (although nowhere near as complicated as that encircling Saturn).  This schematic of the Uranian rings is from Wikimedia Commons.

Today, Uranus is known to possess a complicated ring system (although nowhere near as complicated as that encircling Saturn). This schematic of the Uranian rings is from Wikimedia Commons.

Today, of course, we know this planet more intimately. For example, in 1977, astronomers using the Kuiper Airborne Observatory made another serendipitous discovery – of rings around the planet Uranus. That discovery made Uranus the second known ringed planet in our solar system. Voyager 2 also observed the rings when it passed Uranus in 1986.

Bottom line: British astronomer William Herschel discovered the planet Uranus – first planet to be discovered since ancient times – on March 13, 1781.