Ah, yes! Cybertron is a complete planetary sphere, if that is what you are wondering. It was that way when Primus first found it, I believe...

[He trails off, as that is an era of time when he did not exist, which means it is both fascinating to him and also a little difficult to comprehend.]

However, he cannot return until it is ready for him to inhabit the Core, and as long as he is not here then Unicron is a threat.

What worries me the most is that the chaos-bringer is becoming more active, now, wheras we do not know when Primus will return. We will have to do what we can, in the meantime.