Shocking develomonpment!
Maybe SBURB is a mechanism designed to keep him out by continually creating universes?
Okay, I really need to read this arc again.
Or it's a mechanism designed to perpetually keep him fed.
Or perhaps Lord English has subverted Sburb's original purpose for his own use. This is my guess.
It might not be OUR earth, but one very similar to it. Nobody has specifically said that the 'red' universe is the one the Kids inhabit.
Let's not ignore clear implications when they're presented to us. Note that the advancement command is back to being '==>', which is the kids' advancement command. This is Earth, our Earth, the kids' Earth. Whoever it belonged to before the troll arc, that's whose Earth it is.
I just noticed something, look here at the colors glowing on the edges of Alternia: http://www.mspaintadventures.com/?s=6&p=004510 , the spot between yellow and green is white. For a second, I thought that it was a slip up, but I looked at the constellations around earth and the constellation corresponding to that one is a whitish grey.
I'm not sure which constellation that is, but its between Gemini and Leo.
Cancer. That band is gray because Karkat's color of choice is gray.