They're now finding terrestial planets around other stars around 2 to 5 times the size of Earth. It seems likely that there are quite a few planets similar to Earth out there.
And we may not need to limit ourselves to Earth-like planets, for who knows the various paths evolution can take?
The real problem is that perhaps it is only us Earthlings who have a penchant for Radio waves; or perhaps we've over estimated the distance such signals will travel before being drowned out by the hiss of backgound radiation.
But if we focus on stable systems known to have planets, we may get lucky.
And perhaps we might consider deliberately broadcasting a strong signal into space...
N is the number of civilizations in our galaxy with which we might expect to be able to communicate and drink with down the pub
and
R* is the rate of star formation in our galaxy
fp is the fraction of those stars which have planets
ne is average number of planets which can potentially support life per star that has planets
fl is the fraction of the above which actually go on to develop life
fi is the fraction of the above which actually go on to develop intelligent life
fc is the fraction of the above which are willing and able to communicate
L is the expected lifetime of such a civilization
B is the strength of their Beer
SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.
