Researched
Discovery of Uranus
On 13 March 1781 William Herschel sees a disc that moves against the stars: the first planet found with a telescope, and it doubled the known width of the Solar System.
Open in the interactive tree →Herschel, a musician in Bath, was sweeping the sky with a homemade 6.2-inch reflector when he noticed an object with a disc. He reported a comet, but Anders Lexell's orbit calculation gave a nearly circular path at about twice Saturn's distance, and by 1783 Herschel accepted a planet, the first new one since antiquity. He proposed the name Georgium Sidus after George III; Johann Bode's suggestion Uranus (1782) prevailed. Small mismatches between its predicted and observed positions later led Adams and Le Verrier to predict Neptune.
Prerequisites
- Reflecting Telescope1668Herschel found it with a 6.2-inch reflector he had built himself.
- Newtonian Mechanics1687Orbit calculations showed a planet's path, not a comet's.
Unlocks
- Discovery of Neptune1846Uranus's orbital mismatches pointed Le Verrier and Adams to the unseen planet.