AST251H1 Lecture 12: AST 251 Lecture 12

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST251H1
• Professor: H.Pfeiffer

Document Summary

Earth-like planets can form in certain parts of the galaxy. If too far from the centre, then too little heavy elements. If too close to the centre, then too many devastating supernova explosions that would destroy life. But recent theoretical calculations show that stars change distance to galactic center: earth is special in having plate tectonics which enable co2 cycle to operate and hence ensures the climate stability. Yes, but don"t know how common hot jupiters are (recall biases in et planet detections: there is just right amount of water on earth. But don"t know how common big moons are: several lesser arguments: Drake"s equation: attempts to estimate the number of currently living inhabited, communicating civilizations in the galaxy, 1961, drake wrote this equation >> R = how many stars are being born per year in our galaxy: in units of stars per year , r 10 stars/yr.