The location where water can exist in the liquid form, thus allowing life.

a region within a solar system or galaxy that can possibly sustain living organisms.

A three-dimensinal region of "comfortable" temperatures surrounding every star.

the zone around a star in which a planet can maintain liquid water on its surface

the region around a star where an Earth-like planet can maintain liquid water on its surface.

A region around a star within which a planet can have temperatures that permit liquid water.

In astronomy a habitable zone (HZ) is a region of space where conditions are favorable for the creation of life. There are two regions that must be favorable, one within a solar system and the other within the galaxy. Planets and moons in these regions are the likeliest candidates to be habitable and thus capable of bearing extraterrestrial life.