The Universe
Yours to Discover
Neptune is the eighth planet from the Sun and the first planet to be located through mathematical predictions, rather than through regular observations of the sky. (Galileo had recorded Neptune as a fixed star during observations with his small telescope in 1612 and 1613, but he failed to realize it was actually a planet.)
When Uranus didn't travel exactly as astronomers expected it to, a French mathematician, Urbain Joseph Le Verrier, proposed the position and mass of another as yet unknown planet that could cause the observed |