As a former Asimov fan, I can tell you he passed away about a year and a half ago. I read his book on Alpha Centauri years ago. I recall that Centauri A is almost a twin of our Sun, about 10% larger; Centauri B is about 15% smaller. The two suns are separated by about 2 billion miles (about the distance between the Sun and Uranus, I think). At that distance the effect of a second sun's heat and light would be negligible. Somewhere there would be a point where the gravity from the two stars would meet, just as there is a point where the gravity of the Earth and Moon overlap. How about a planet in a Lagrangian orbit between the two stars? You need to figure out what the 'viable' distance from the primary star an earth-like planet can exist. Good Luck. Kemper : :