The habitable zone is the intersection of two regions the solar, which is where liquid water can exist and the other, the area within a galaxy where a solar system can remain stable for billions of years.[1]
Planets and moons in these regions are the likeliest candidates to be habitable and thus capable of bearing extraterrestrial life similar to our own.[1]
Earth and Gliese 581 g are both located in the middle of their respective habitable zone.[1]
