SPOILER ALERT: If you haven’t seen Sometimes a Great Notion yet, and care about spoilers for some reason, stop reading now. If you haven’t seen it yet, you should also stop reading now, because you’re obviously not a Battlestar fan, and therefore suck.
I’ll just some out and say it: the planet that the fleet arrived at in Revelations is not Earth. Or at least is not our Earth, the planet that was shown in Crossroads, Part 2 at the end of Season 3.
You might be asking where or what is my proof? Its quite simple. Nothing that is shown in BSG is done by accident. The Darth Mojo blog goes into great detail about the agonizing detail that the artists and producers go into for each shot. In his podcast, Ron Moore mentioned that he showed Earth that was clearly Earth with a clear shot of North America. He did that to show the audience that the series was clearly going to end and that the fleet would find Earth.
However, we were never shown the surface of the planet in Sometimes a Great Notion. Ever. All we ever got was an oblique angle of the planet’s terminator with the fleet silhouetted against the sun. We saw ships flying through clouds, but no glimpse of the continents or large swath of surface.
If the planet in Sometimes a Great Notion was Earth, it would have been clearly shown as such. It wasn’t shown; its not Earth. Look at my proof:
Crossroads Earth. I can see my house from here!
Of course we’ll get more information over the course of the next nine episodes, but its far more fun to speculate!