List of former planets

This is a list of astronomical objects formerly widely considered planets under any of the various definitions of this word in the history of astronomy.

As of 2024, there are eight official planets in the Solar System per the International Astronomical Union (IAU),[1] which has also established a definition for exoplanets.

The moons discovered around Jupiter, Saturn and Uranus after the advent of the telescope were also initially considered planets by some.

One of these, Eris, was widely hailed as a "new planet", which prompted the 2006 recategorization of solar system bodies.

By 1855 the number of known bodies in the asteroid belt had grown to 15, at which point astronomers started distinguishing these from the eight known major planets.