PopSci reports: Each star in the Milky Way shines its light upon at least one companion planet, according to a new analysis that suddenly renders exoplanets commonplace, the rule rather than the exception. This means there are billions of worlds just in our corner of the cosmos. This is a major shift from just a few years ago, when many scientists thought planets were tricky to make, and therefore special things. Now we know they’re more common than stars themselves.
“Planets are like bunnies; you don’t just get one, you get a bunch,” said Seth Shostak, a senior astronomer at the SETI Institute who was not involved in this research. “So really, the number of planets in the Milky Way is probably like five or 10 times the number of stars. That’s something like a trillion planets.”
Of course there’s no way to know, at least not yet, how many of these worlds could be hospitable to forms of life as we know it. But the odds alone are tantalizing, Shostak said.
“It’s not unreasonable at this point to say there are literally billions of habitable worlds in our galaxy, probably as a lower limit,” he said. “Maybe they’re all sterile as an autoclave, but it doesn’t seem very likely, does it? That would make us very odd.”