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Terraforming: why the Moon is a better target than Mars
(bigthink.com)
Cover author: Michał Kałużny http://astrofotografia.pl/
The difference is huge. The moon is practically right next door to us (384 megameters). Mars closest point to Earth is 54000 megameters.
It's like having a friend living 384 meters down the road vs living 54-150 kilometers away.