The Drake Equation

Once upon a time, back in the heady days of 1961, Dr. Frank Drake introduced to the world an equation that could be used to calculate the number of extraterrestrial civilisations in or galaxy with communications technology. The equation was

N = R_* x f_p x n_e x f_l x f_i x f_c x f_c x L

Simple, eh? Just plug in the values, and you've got the number of planets for which it's worth devoting seti@home cycles. Sadly, no-one has much of a clue what any of the values are.

Which is where you come in.

Simply fill in the values below with your best guess, and behold the number of ETs out there. Save your answer, and when we've examined all the stars in the galaxy, compare the actual answer to your estimate. There'll be a prize for whomever gets closest.

Oh, and being thoroughly modern chappies here at Work in Progress, we have no truck with those 'fraction' things. Enter a percent instead. Please.

R_* - Rate of formation of suitable stars (how many new stars are formed each year):		More on R*
F_p - The fraction of suitable stars with planets:	%	More on Fp
N_e - Number of Earth-like planets per system:		More on Ne
F_l - Fraction of earth-like planets on which life evolves:	%	More on Fl
F_i - Fraction of those planets on which intelligence evolves:	%	More on Fi
F_c - Fraction of those planets on which technology develops:	%	More on Fc
L - Lifetime of any civilisation lucky enough to get to F_c:	years	More on L

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