The possibility of life on other planets has long fascinated moviegoers, scientists, and stargazers alike, but answers have been elusive. Do other planets, like Earth, circulate around stars in their respective solar systems? Surely. The first was discovered in 1988.
But are these faraway masses, known as exoplanets, able to sustain life? No one knows.
On Monday, an international team of astronomers from MIT, Europe, and elsewhere announced a breakthrough that may help answer that question, thanks to a specially made 60-centimeter telescope based in Chile.
Using that advanced instrument, called TRAPPIST, the team this fall detected three planets that may be habitable, orbiting a dwarf star just 40 light years from Earth.
“This is a paradigm shift,” said Julien de Wit, an atmospheric scientist at the Massachusetts Institute of Technology. “These planets are the best shots for us to search for other habitats, and maybe even life.”
Initial observations revealed all three planets have regions with temperatures well below 400 Kelvin — or 260 degrees Fahrenheit. This means, according to the study’s astronomers, all three planets could sustain liquid water and life, at least in some areas.
“The three discovered planets are the first places for which we could find life outside our solar system,” said Michael Gillon, a lead author of the study from the University of Liège in Belgium.
The team of researchers has preliminarily named the planets “the Red Worlds.”
The star that the planets orbit has been dubbed TRAPPIST-1, in honor of the telescope that led to the discovery. The two innermost planets orbit TRAPPIST-1 in 1.5 and 2.4 days, respectively, and the third planet orbits the star between four to 73 days, according to a MIT news release.
All three have similar masses to Earth and Venus, which have a radius of near 4,000 miles.
“The two planets closest to the star may have day sides that are too hot, and night sides too cold, to host any life forms,” the release stated. “However, there may be a “sweet spot” on the western side of both planets — a region that still receives daylight, but with relatively cool temperatures — that may be temperate enough to sustain conditions suitable for life.”
The third planet may be entirely within the habitable zone, the team found.
The study has set the scientific community abuzz, in part because of the unique process that led to the discovery. Most high-powered scientific telescopes focus on ultra-bright, hot stars like the sun, de Wit said. But the MIT team, which principally collaborated with Gillon and other scientists from Belgium, focused on small, cooler stars.
These cooler stars are so dim that they are sometimes invisible to optical telescopes. But TRAPPIST used infrared wavelengths to detect the planets surrounding such faint dwarf stars, de Wit said. This type of dwarf stars represents about one-third of all stellar objects, which had previously been unexplored for planets, Gillon said.
“We designed TRAPPIST not only to search for planets around ultracool dwarfs but also to confirm and study planets found by other projects targeting bigger stars and to observe comets and asteroids,” Gillon wrote by e-mail Monday.
“Thanks to this discovery, we now know that a significant fraction of ultracool dwarfs are orbited by planets of the size of the Earth that could have the right surface conditions to host life,” Gillon added.
Other key information, such as the atmospheric makeup of the planets, is unknown. But Gillon and de Wit said more data will become available as newer, more specialized technology focuses on the “Red Worlds.”
“There’s a huge scientific return in the next decade. The spirits are really high,” de Wit said. “This is the beginning.”
The science of exoplanets has accelerated rapidly in recent years. Since the first discovery in 1988, the Extrasolar Planets Encyclopaedia has named 2,111 confirmed exoplanets in 1,354 planetary solar systems and 510 multiple planetary systems.
About 1 out of 5 exoplanets have habitable climate zones, studies have shown, so there could be almost 11 billion in the Milky Way galaxy alone. Still, scientists have struggled to find an exoplanet whose atmosphere was ripe for study. In an essay published last year, two other MIT researchers highlighted the need for a revelatory finding.
“Despite the progress in exoplanet atmosphere observations and theory, we are severely data-limited in our study of exoplanet atmospheres of any kind,” the study said. “Very few exoplanets are suitable for detailed atmosphere observations.”
That is why this discovery is so crucial, de Wit said. Because the three newly discovered exoplanets are only 40 light years away from Earth, scientists can now perform the atmospheric studies that once seemed elusive, reenergizing the search for life beyond Earth.
“This is a clear game-changer,” de Wit said.
Gillon, who described the discovery as “just amazing,” celebrated by raising a glass with some friends. In keeping with the day’s theme, he chose a Trappist beer.