Astrobiological Copernican Limits equation is N = N* x fL x fHZ x fM x (L/╧ä'). The parameters are N is the number of civilizations in the galaxy, N* is the total number of stars in the galaxy, fL is the percentage of stars that are at least 5 billion years old, fHz is the percentage of stars which host a suitable planet for supporting life, L is the average lifetime of a civilization, and ╧ä' is the average amount of time available life to develop on a planet.