Pluto was once the most distant planet from the Sun and by far the smallest in our Solar System. However, in 2005 astronomers found an object in the outer Solar System, called Eris, which they thought was bigger than Pluto. From this discovery, Pluto’s fate was decided: it would no longer be called a planet. Instead, astronomers created the new title ‘dwarf planet’ for Pluto, Eris and other similar objects. This picture shows an artist's drawing of what the dwarf planet Eris looks like.
Credit:
ESO/L. Calçada