Can't get the Spoiler tags to work for some reason...... SO:
POSSIBLE SPOILERS BELOW ( assuming you haven't seen the mid season finale )
I don't think things are what they seem.
I get a nagging suspicion this isn't Earth, but Terra, or at least a past Human colony world that the 13th Tribe thought was Earth.
What if the 13th tribe arrive at this world and find a Human civilisation... the 2 sides try to live together but the 13th are like outsiders, tensions rise and BOOM!
All of that could have happened in the same time frame as the colonials leaving Kobol and arriving at Caprica etc....
In some spoilers/Rumours i read today, one of the production team said the planet isn't what it seems.
Maybe this world is another stepping stone to Earth.
I admit that if it is Earth, I would like information on what happened... and I will feel really betrayed if the colonials have arrived in our past.
Personally I want the Colonials and any Cylons that join them to have a genuine happy ending, I really want to see them arrive at a place where there are people, where there are Children and families living in peace. After the conditions the people of the fleet have lived with, that seems like a true payoff....... basically everything that Voyager wasn't. Even if there is major misery before that ( more than usual ). Even if the world they arrive at is a new Human home world, I want the colonials to see the full history of Humanity that stems from Earth