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.
1.) He called it earth
2.) Bob Dylan
Bad evidence. Watch:
1.) We live on Mars. Just because you name something Earth doesn't mean it's the only one.
2.) Bob Dylan = Sam Anders
(They implied Anders wrote the song, don't believe? Listen to the podcast. Ron Moore says specifically that it is intended that Anders wrote the song.) The fact they used watchtower doesn't mean that meant that Dylan wrote it.