Uranus misbehaves
In 1781 William Herschel discovered Uranus. But the new planet strayed from its calculated orbit. The astronomer Alexis Bouvard suspected that an unknown planet was pulling on it.
Seen, sought, found
- 1612Galileo draws Neptune – as a star
- 1781Herschel discovers Uranus
- 1846Galle finds Neptune
Galileo had Neptune in his telescope as early as 1612 but took it for a fixed star.
Less than a degree off
1°off from the prediction
John Couch Adams and Urbain Le Verrier independently calculated where the unknown planet had to be. On 23 September 1846 Johann Galle searched with a telescope – and found Neptune less than one degree from Le Verrier's prediction.