be in orbit around it. “It’s like standing in front of a lamp and throwing a flea across it,” said Adam Burgasser, a member of the team which discovered the planets. “It was only a 1 percent dip in light, but the specific pattern was a good sign of orbiting planets.”
Because TRAPPIST-1 is fairly close (on cosmic scales), only 39 light-years away from Earth, its planets represent a perfect opportunity for study. Using the TRAPPIST telescope network as well as some larger telescopes, astronomers were able to determine that all three of TRAPPIST-1’s planets are only slightly larger than Earth but much closer to their star. The two innermost planets orbit the star in 1.5 and 2.4 Earth days.
It is possible that, like Earth’s moon, each of these two planets is tidally locked, with one side always facing the star and the other side always dark.The third planet, which has proven harder to study than the others, has a less well-determined year of somewhere between 4.5 and 73 Earth days. As Gillon explained, “the structure of this planetary system is much more similar in scale to the system of Jupiter’s moons than to that of the Solar System.”
Beyond the system’s general structure, it’s hard to say much about these planets right now. However, with the James Webb Space Telescope launching in 2018, astronomers should be able to analyze the planets’ atmospheres “and further down the road, which is within our generation, assess if they are actually inhabited,” study co-author Julien de Wit said. “All of these things are achievable, and within reach now. This is a jackpot for the field.”
Since about 15 percent of stars close to the Sun are ultracool dwarfs like TRAPPIST-1, this could open vast new possibilities for the search for planets and life in our neighborhood. As Gillon said, “Exciting scientific adventures are now beginning.”