7
18 DISCOVERMAGAZINE.COM
SEVEN WHOLE
NEW WORLDS
❯
IMAGINE LOOKING UP at the night
sky and seeing planets looming larger
than our moon. It sounds like science
fiction, but astronomers discovered it could
be reality for the TRAPPIST-1 system, which
boasts seven Earth-sized worlds — a record.
Some orbit almost as close to each other as
the moon is from Earth.
In May 2016, members of the Belgian
TRAPPIST team announced their small
telescope had turned up three potentially
habitable planets orbiting a star just
40 light-years away. Then they turned to
NASA’s Spitzer Space Telescope to get more
detail, and it revealed there were actually
a whopping seven. Three orbit in the star’s
conservative habitable zone, the region
where liquid surface water might exist. The
results appeared in Nature in February.
TRAPPIST-1 is a cool red dwarf barely
bigger than Jupiter in diameter, but about 84
times heavier, giving it just enough mass toignite into a star. Such stars can have violent
eruptions early on, but are extremely stable
afterward. So if the planets didn’t cook,
life could have later evolved. And research
announced in August shows TRAPPIST-
could be as much as twice our sun’s age. The
short distance between worlds also means
microbes could planet-hop on space rocks, as
described in a June study in the Proceedings
of the National Academy of Sciences.
“[The] TRAPPIST-1 discovery officially
opened a whole new chapter of space
exploration,” says Julien de Wit, an MIT
researcher who co-discovered the planets.
JOHN WENZ NASA/JPL-CALTECH