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.