Robby
Helper Bot

At the end of the finale we found a sad mess of a crew standing around on what we presumed was a broken and radioactive former Earth. The melancholy was thick and you could almost hear the phrase, "all this has happened before," in the air. The Science of Battlestar Galactica wagers a few guesses based on the looks of the terrain. It could be Brooklyn, if you look closely at the bridge, but it's more likely, say the science experts, that this isn't Earth at all.
First they point out the Lt. Gaeta said the constellations were a match to coordinates that were never fully realized. And if they were the constellations from the Temple of Athena in Kobol, then they could very well be incomplete.
What evidence do we have that this irradiated planet is really Earth? Lt. Gaeta, when checking to see whether the fleet had jumped to the right spot, said that the visible constellations are a match. But a match with what set of data? Lee said that they had "projected a course to the signal" and that it would probably take some revising. That tells me the Colonial beacon signal did not include a 3-d starmap. Is Gaeta checking the constellations with what the jump calculations predicted the resulting constellations should look like? That would only prove that they jumped to where they expected to jump — it wouldn't prove that they had jumped to Earth.
It then explains that perhaps they landed on an entirely different planet, one that is similar to Earth but not the genuine article.
In our space neighborhood there are at least three other sunlike stars that possibly could support earthlike planets. If the fleet jumped into the Alpha Centauri system instead of ours, for example, that might fit Starbuck's recall of seeing a triple star system on her trip to "Earth". The Alpha Centauri system consists of Alpha Centauri A, a Type G star that's a very slightly larger version of our own sun — replace our local star with Alpha Centauri A and the average person would be hard pressed to notice the difference for a while; Alpha Centauri B, an orange star about 7/8 the size of the sun, orbiting with Alpha Centauri A in way that keeps the two stars an average of 24.4 astronomical units (about 3.8 billion kilometers) apart; and Alpha Centauri C, a red dwarf star also known as Proxima Centauri, which orbits around the A and B stars about 1/10 of a light year distant.
If Gaeta was checking the position of the zodiacal constellations with a sketch made from the Temple of Athena data, he's out of luck. As seen from Alpha Centauri, those constellations would be virtually identical to those seen from Earth, the chief difference being that Castor and Pollux, the Heads of the Gemini Twins, don't quite line up with their bodies. If Gaeta had incomplete data, or if the constellation Gemini was not visible for some reason (being occulted by Alpha Centauri, for example), he'd be absolutely correct in reporting that all "visible" constellations are a match, even though the fleet would be in the wrong place.
In the same way, the fleet could have arrived at Tai Ceti or Epsilon Eridani, two other type G sunlike stars in our local neighborhood. The zodiacal constellations as seen from those systems would be more distorted, especially around the Cancer-Leo and Aries-Taurus regions. But again, if Gaeta's data are sketchy and the local star is blocking out the appropriate regions of the zodiac, the rest of the constellations should pass muster.
The big BSG clue for this being the wrong planet is there were no recognizable continent wide shots, like in the end of the third season when they showed Earth and you could clearly point out North America. There was no point of reference for the audience, so it's really anyone's guess where they could be at this point.If Gaeta was checking the position of the zodiacal constellations with a sketch made from the Temple of Athena data, he's out of luck. As seen from Alpha Centauri, those constellations would be virtually identical to those seen from Earth, the chief difference being that Castor and Pollux, the Heads of the Gemini Twins, don't quite line up with their bodies. If Gaeta had incomplete data, or if the constellation Gemini was not visible for some reason (being occulted by Alpha Centauri, for example), he'd be absolutely correct in reporting that all "visible" constellations are a match, even though the fleet would be in the wrong place.
In the same way, the fleet could have arrived at Tai Ceti or Epsilon Eridani, two other type G sunlike stars in our local neighborhood. The zodiacal constellations as seen from those systems would be more distorted, especially around the Cancer-Leo and Aries-Taurus regions. But again, if Gaeta's data are sketchy and the local star is blocking out the appropriate regions of the zodiac, the rest of the constellations should pass muster.
[Galactica Siterep and The Science Of Battlestar Galactica]
(Via IO9)