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A28 SCIENCE
Saturday 22 april 2017

Another nearby planet found that may be just right for life

SETH BORENSTEIN Outside astronomers have planets in or near the habit-
AP Science Writer already put this new planet able zone found circling a
WASHINGTON (AP) — As- near the top of their must- star called Trappist-1 earlier
tronomers have found yet see lists for new ground and this year, but it in a different
another planet that seems space-based telescopes. direction. And in August,
to have just the right Gold- “This is the first one where astronomers found that
ilocks combination for life: we actually know it’s the nearest planet to Earth
Not so hot and not so cold. rocky,” Charbonneau said. outside our solar system,
It’s not so far away, either. “We found a planet that only 25 trillion miles away,
This new, big, dense planet we can actually study that also could have the right
is rocky, like Earth, and has might be actually Earth- temperature for life, but as-
the right temperatures for like.” tronomers can’t get a peek
water, putting it in the hab- Make that super-sized, be- at its atmosphere.
itable zone for life, accord- cause it belongs to a class “If you picture the Milky
ing to a study published of planets called super- Way as the size of the Unit-
Wednesday in the jour- Earths that are more mas- ed States, then these sys-
nal Nature . sive than Earth but not tems are all within the size
It’s the fifth such life-possi- quite the size of giants Nep- of Central Park,” Charbon-
ble planet outside our so- tune or Jupiter. neau said. “These are your
lar system revealed in less Compared to Earth, the neighbors.”
than a year, but still rela- new planet is big, push- The latest discoveries have
tively nearby Earth. Rocky In this artist tendering provided by M. Weiss Harvard-Smithso- ing near the size limit for their founders at odds over
planets within that habit- nian Center for Astrophysics, a newly-discovered rocky exo- rocky planets. It’s 40 per- which of the planets are
able zone of a star are planet, LHS 1140b. cent wider than Earth but it the most promising. Char-
considered the best place Associated Press has 6.6 times Earth’s mass, bonneau said recent stud-
to find evidence of some ered in 1995, but thanks to The latest discovery, called giving it a gravitational ies show that the Trappist
form of life. new techniques and espe- LHS 1140b, regularly passes pull three times stronger, planets may not be rocky
“It is astonishing to live in a cially NASA’s planet-hunt- in front of its star, allowing Charbonneau said. A per- like Earth, while Trappist
time when discovery of po- ing Kepler telescope, the astronomers to measure its son weighing 167 pounds discoverer Michael Gillon
tentially habitable worlds number of them has ex- size and mass. That makes would feel like 500 pounds said the newest planet has
is not only commonplace ploded in recent years. As- astronomers more confi- on this planet. While many such intense gravity that
but proliferating,” said MIT tronomers have now iden- dent that this one is rocky, super-Earths are too big to its atmosphere may be
astronomer Sara Seager, tified 52 potentially hab- compared to other recent have the right environment smooshed down so tele-
who wasn’t part of the itable planets and more discoveries. for life, 1140b is just small scopes can’t get a good
study. than 3,600 planets outside In the next several years, enough to make it a good look at it. Seven outside
The first planet outside our our solar system. new telescopes should be candidate. Thirty-two of the astronomers said the Milky
solar system was discov- able to use the planet’s potentially habitable plan- Way is big enough for all
path to spy its atmosphere ets found so far are consid- the discoveries to be excit-
in what could be the best- ered super-Earth sized. The ing, requiring more explor-
aimed search for signs of new planet was found us- ing. Yale astronomer Greg
life, said Harvard astrono- ing eight small telescopes Laughlin, who wasn’t part
mer David Charbonneau, in Chile and help from an of any of the teams, praised
a co-author of the study. If amateur planet-hunter, all the new findings but said
scientists see both oxygen Charbonneau said. the Trappist planets seem
and some carbon in an at- In the constellation Cetus, it too light and the new one
mosphere, that’s a prom- is 39 light years or 230 trillion too dense for his taste: “I
ising sign that something miles away. So are a group wouldn’t book a trip to any
could be living. of seven mostly Earth-sized of these planets.”q