BBC: Galaxy has 'billions of Earths'

Extrapolation done by Dr. Alan Boss of the Carnegie Institution of Science.  Based upon the 300+ planets found so far he has estimated that there are perhaps billions of earthlike planets in the galaxy.

So using his number that places us halfway through the Drake equation.

N = R* × f_p × n_e × f_l × f_i × f_c × L

[link: Drake Equation]

Of course the numbers get harder to know (or estimate) the further towards the right side of that equation.  But just think we didn’t even have the data to make an educated guess five years ago.