how did they work out the orbits of the outer planets?

Question

I guess now they use a mix of observational data and supercomputer calculations, but how did they figure out the orbits of Uranus, Neptune and Pluto (no arguments about Pluto’s status please!) on the discovery of those?

In: 4

Answer 1

Uranus’ orbit was calculated from observations of the planet in 1783. The observed orbit was slightly different from the calculated orbit which led to the thought that this might be caused by another planet. Calculations were made to predict an orbit of a planet that could cause these effects on Uranus and that led to the discovery of Neptune.