They blew up the moon
One of Eggman and Shadow’s power plays in Sonic Adventure 2 is demonstrating the Eclipse Cannon’s capabilities by blowing a hole through the moon. This plot beat has become kind of a meme at this point, as most Sonic games that follow don’t reflect it. Sega tried to explain this as the moon having turned, so every time we see it in subsequent games we’re just seeing the side that isn’t broken. [The moon is in a synchronous rotation orbit with the Earth, and as such never turns from our perspective—Nerdy Ed] But more recently, the Shadow Generations: Dark Beginnings animated series has shown the moon broken with a ring of shattered pieces around the remaining satellite. In Sonic the Hedgehog 3, it looks like they’re slicing off part of the moon’s lower hemisphere, to which Sonic responds, “Somebody better call Google Maps.” Groan.
