If you can move an entire planet, you could just have moved it to the other side of the sun in the Earth orbit. No tidal problems, you still have your planet, aliens don't have to abandon their houses, or notify the utilities and paperboy of your address change or conduct an untidy genocide. It's likely that we wouldn't even know about the arrival of their planet for another several decades. (We have a set of stereo-optic satellites observing the sun, but I don't think they're looking in that vicinity.)
If you have technology to do that, you likely could just send a "Stargate" platform to the other side of the sun with loads of power to accomplish this. They knew this was happening, why else would they have sent Sophia and her merry tribe here 60 years ago? It's not like they didn't have time to prepare. (Not that seeing a huge burning planet in the sky eclipsing the moon wasn't a cool effect.)
I was pretty eager to see another season, but this stretched incredulity too far. Sorry, I won't miss this series ignominious end.
I like continuing storyline shows, but this one lost it's brains.....
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