NASA's prolific Kepler space observatory never ceases to amaze planet hunters. Last week's announcement of two "super-Earth" type planets sharing the habitable zone around the red dwarf star Kepler-62 further ratcheted up our optimism that life-bearing planets are all over the galaxy.
Kepler scientists explained that the only data the stellar transits (when the planets pass in front of their stars) have to tell us is the planets' orbits and diameters. Still it's hard for experts to resist speculating that these planets "may have polar caps," or may be "water worlds," or, "we may have found the first ocean planet," The scientists finally did acknowledge in the April 18th NASA press conference that they were doing "a lot of arm waving."
Kepler-62: A Star System With Two Earths?
The same would be true for my imaginary alien astronomer Zork, on a planet 1,000 light years away. Zork reports to colleagues that photometric observations of the yellow dwarf star Sol (a.k.a. our sun) reveals three planets inside or on the edge of Sol's habitable zone: Venus, Earth and Mars. He considers this a great SETI target because you get three inhabitable worlds for the price of one observation!