Whose work showed that the Sun, and not the Earth, sits at the centre of the solar system?

1. Early astronomers placed the Earth at the centre with everything orbiting it. 2. That picture could not explain why planets sometimes appear to move backwards. 3. Copernicus deduced instead that the Sun sits at the centre. 4. He also placed the known planets in the right order out from the Sun. _Source: Siyavula Natural Sciences Grade 7 (CC BY 4.0), The discovery that the Sun is at the centre of the solar system and not the Earth_