The area in a solar system where life is most likely is called the circumstellar habitable zone ( CHZ ) . The places in a galaxy where life is most likely is called the galactic habitable zone ( GHZ ) .
Life is most likely to form within the circumstellar habitable zone ( CHZ ) within a solar system , and the galactic habitable zone ( GHZ ) of the larger galaxy ( though research on the latter point remains in its infancy ) .