Quote:
Originally Posted by bill_mchale
Yes, we are discovering planets at a terrific rate, but our methods are still biased towards detecting big planets in tight orbits around their stars.Bill
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The Kepler transit method used by NASA can detect smaller and further-out planets; it just takes longer because they need to to track the star for multiples of the planet's orbit. Give'em time to acquire the data.
Beyond that, and bearing on life-probabilities, is what we're finding out about planet formation processes and the (limited) amount of time that the planet-formation clouds can survive. And about the composition of those clouds. The latter suggests that earthlike planet formation requires a lot of heavy elements in the cloud which requires supernova ejecta from second or third generation stars. Which in turn suggests there may not be many earthlike worlds that are older than Earth.
More data is needed to refine the models but so far it doesn't look like the older stars are good places to look for earth-like worlds.
(Very low odds for a Darkover or a Krypton, for example.)