For decades, astronomers have searched for a planet that not only had the potential to support life, but could be studied from Earth. This week they didn’t finally find one—they found three.
“This really is a paradigm shift with regards to the planet population and the path towards finding life in the Universe,” said Emmanuel Jehin, one of the co-authors of the Belgian study that made the discoveries.
The three roughly Earth-sized planets revolve around a star called TRAPPIST-1, which scientists describe as “ultracool.” That’s not just because they like it so much—TRAPPIST-1 is cooler and dimmer than our sun, which is why we can study its planets so easily.
The reason has to do with light—the dimmer the star, ironically, the better scientists can see the things revolving around it. In the case of TRAPPIST-1, astronomers can study the atmosphere of each of its three planets by examining how it affects light passing through it. And with enough information, scientists can determine whether those atmospheres can support life.
"Systems around these tiny stars are the only places where we can detect life on an Earth-sized exoplanet with our current technology,” said Michael Gillon, lead author of the study. “So if we want to find life elsewhere in the Universe, this is where we should start to look.”
So scientists have started to look. The next question is what they'll find.