Terra Obscura is the name given to another Earth by Tom Strong. It is not in a parallel Universe, but rather on the far side of the Galaxy from Tom's own Earth. Tom Strange is revealed to have run across the Milky Way for 30 years to reach Tom Strong for help in stopping an alien menace which killed or imprisoned most of the science heroes of Terra Obscura. Strong himself theorized that the duplicate Earth "must be due to some near-inconceivable fluke of mathematics, of statistical probability".