Cav's Place

Yesterday’s announcement confirmed what is by far Kepler‘s best discovery to date: Kepler-62f. The release also mentions six more planets in the two announced systems, and while Kepler-62b, c and d, as well as Kepler-69b, are in very tight orbits and therefore scorched by their stars, Kepler-62e and 69c are also in their stars’ habitable zones. However, they are close to the inner edge of those zones, in orbits roughly equivalent to that of Venus in our own solar system, and considering the fact that they’re 60% and, respectively, 70% larger than Earth, it seems quite likely that they have very thick atmospheres and experience a runaway greenhouse effect. After all, the calculated temperatures are 270°K for Kepler-62e and and 299°K for Kepler-69c, according to a standard method that ignores atmosphere and would make Earth’s average temperature 255°K, while in fact it’s 288°K and increasing.
Kepler-62f, on the other hand, is only 40% larger than Earth and pretty much in the middle of its star’s habitable zone, its position being comparable to being about two thirds of the way between Earth and Mars in our solar system. Of course, it is rather cold out there, and its calculated average temperature is a mere 208°K, but even an Earth-like atmosphere should allow at least a few areas to occasionally be above freezing, and its larger size should normally help it hold on to a thicker atmosphere that’d increase the temperature even more, so it really does seem almost ideal. In addition, the star in question is a K dwarf, K2 to be exact, and that type of stars are considered to be the best bets for life, seeing as they are more numerous and live significantly longer than larger ones, such as the Sun, which is a G2, while at the same time being stable and having their habitable zones sufficiently far away to avoid tidal locking and reduce each individual planet’s risks in the event of coronal mass ejections and other similar events, which isn’t the case for class M ones. To prove this fact, this particular star is estimated to be about seven billion years old and still in its prime, so life has had plenty of time to develop on its planets… Though, of course, at the same time it had plenty of time to be wiped out or, if it followed our pattern, wipe itself out.
There are other problems as well, such as the star’s low metallicity and the fact that, despite being the smallest super Earth found in its star’s habitable zone so far, a rocky planet 40% larger than Earth would have a significantly higher mass and therefore anything living on it would have some problems with gravity. However, seeing as we are still looking for planets that are located within their stars’ habitable zones and are no more than 25% larger than Earth, which is the upper limit for “Earth-size” planets, and Kepler-62f’s exact location within its solar system seems so right for a planet its size, one can’t help but wonder whether there’s somebody there who is, or at least has the capacity to be, looking towards us and wondering the same thing.