In the search for Earth-like planets, astronomers zeroed in Tuesday on two places that look awfully familiar to home. One is close to the right size. The other is in the right place.
European researchers said they not only found the smallest exoplanet ever, called Gliese 581 e, but realized that a neighboring planet discovered earlier, Gliese 581 d, was in the prime habitable zone for potential life.
While Gliese 581 e is too hot for life “it shows that nature makes such small planets, probably in large numbers,” Marcy commented. “Surely the galaxy contains tens of billions of planets like the small, Earth-mass one announced here.”
I don’t think most people recognize the significance of science like this. Scientists will never find themselves short of planets to observe. Our small, insignificant star has 8 planets around it. Assuming the average star has only 1 planet in its orbit, that’s still trillions of planets. The number is probably less than 1 per star, I’d guess, but who knows? It’s at least certainly unfathomably high. A small fraction per star would still yield a huge number; there are more stars in the Universe than grains of sands on all the beaches of Earth. Not enough people appreciate that fact.