This may not be 'our Earth'. What have they done to let us believe this is the Earth we know. The have not shown the moon or any other solar objects that we could reconize, also no reconizable land masses or anthing Earth specific. We know from Tyrol's flashback that they had cars of some sort, but they never showed them, we only heard them.
I believe that this is RDM's way of pulling the OldBsg's Terra element on us.
I don't know. Who's to say "our Earth" even exists in BSG? If this isn't "our Earth" it's as close as we're going to get, I think.