Could There Be Life on the New Earth-Size Kepler Planets?
Published December 20, 2011  | TechNewsDaily  For life as we
know it to arise on another planet, scientists think the alien
world must have three key ingredients: organic molecules that
can form complex structures, energy to jiggle those molecules,
and liquid water for them to jiggle in. It's a short recipe, but
nonetheless, only planets that are extremely similar to Earth
can possibly have all three items in stock.  If a planet is much
closer to its star than we are to ours (and assuming that star
is similar in size to our sun), all the water on its surface
will evaporate in the heat. If it's much farther away, all its
water will freeze. Similarly, planets much larger than Earth are
gaseous, with no solid surface for an ocean to slosh around on,
while those much smaller wouldn't have had enough gravity to
form in the first place. Thus, in the search for "candidate
planets" which could host alien life, "alien Earths" are the
Holy Grail.  In a paper p