Solar system · Planet
Planet
Neptune
The planet found with a pencil: its position was calculated from the pull it had on Uranus before anyone saw it.
Discovery
Urbain Le Verrier predicted where it would be, and Johann Galle found it within a degree of the spot on the first night of searching, 23 September 1846.
Did you know
It takes 165 years to orbit the Sun; it completed its first full orbit since discovery in 2011.