Mercury

Mercury
Mercury is a planet located in the Sol System and is the 1st planet its host star with its neighboring planet being Venus. Mercury has the shortest orbit out of all the 8 planets in the Sol System with it only being 88 days long but it takes nearly its whole orbit to complete a Mercurian day with a full rotation taking 55 days. Mercury also does not have an atmosphere with it being essentially like a larger version of Earth's moon.

Native Life
Since Mercury doesn't have an atmosphere it can't doesn't and can't support life.

Colonization
Mercury has been fully colonized by Humans by the time of That One Reality and has been turned into a scientific research base for studying the sun and also has large mining operations on its surface.