>>544823759
>Earth
Sonic's World didn't have a name until the Meta Era. 地球 (or Chikyū) was never used in Japanese and it was called 地上(Chijō) or just the ground/land since Sonic 3 .

Calling Sonic's World "Earth" was a localization thing.

This is your reminder that "Sonic's World" never had a canon name, and the calling it proper noun "Earth" is a Meta Era concession