How did sonic get to earth

Eggman used a machine to activate Chaos Control when he had captured Cream and Cheese and Sonic tried to save them. Chaos Control warped Sonic and his freinds into another universe and onto Earth.
The answer on top is for Sonic X's canon. In the main canon of the games, Sonic was already born on Earth. Simple as that. Japan loves to make their own fantasy version of Earth in animes, mangas, and video games. Sonic the hedgehog is one of them.