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NASA's planet-hunting telescope has found 10 new planets outside our
solar system that are likely the right size and temperature to potentially have
life on them, broadly hinting that we are probably not alone. After four years
of searching, the Kepler telescope has detected a total of 49 planets in the
Goldilocks zone. And it only looked in a tiny part of the galaxy, one quarter
of one percent of a galaxy that holds about 200 billion of stars.
Seven of the 10 newfound Earth-size planets circle stars that are just
like ours, not cool dwarf ones that require a planet be quite close to its star
for the right temperature. That doesn't mean the planets have life, but some of
the most basic requirements that life needs are there, upping the chances for
life.
"Are we alone? Maybe Kepler today has told us indirectly, although
we need confirmation, that we are probably not alone,'' Kepler scientist Mario
Perez said in a Monday news conference. Outside scientists agreed that this is
a boost in the hope for life elsewhere. "It implies that Earth-size
planets in the habitable zone around sun-like stars are not rare,'' Harvard
astronomer Avi Loeb, who was not part of the work, said in an email.
The 10 Goldilocks planets are part of 219 new candidate planets that
NASA announced Monday as part of the final batch of planets discovered in the main
mission since the telescope was launched in 2009. It was designed to survey
part of the galaxy to see how frequent planets are and how frequent Earth-size
and potentially habitable planets are. Kepler's main mission ended in 2013
after the failure of two of its four wheels that control its orientation in
space.
It's too early to know how common potentially habitable planets are in
the galaxy because there are lots of factors to consider including that Kepler
could only see planets that move between the telescope vision and its star,
said Kepler research scientist Susan Mullally of the SETI Institute in Mountain
View, California.
It will take about a year for the Kepler team to come up with a number
of habitable planet frequency, she said. Kepler has spotted more than 4,000
planet candidates and confirmed more than half of those. A dozen of the planets
that seem to be in the potentially habitable zone circle Earth-like stars, not
cooler red dwarfs.
Circling sun-like stars make the planets "even more interesting and
important,'' said Alan Boss, an astronomer at the Carnegie Institution, who
wasn't part of the Kepler team. One of those planets — KOI7711 — is the closest
analog to Earth astronomers have seen in terms of size and the energy it gets
from its star, which dictates temperatures.
Before Kepler was launched, astronomers had hoped that the frequency of
Earth-like planets would be about one percent of the stars. The talk among
scientists at a Kepler conference in California this weekend is that it is
closer to 60 percent, he said.
Kepler isn't the only way astronomers have found exoplanets and even
potentially habitable ones. Between Kepler and other methods, scientists have
now confirmed more than 3,600 exoplanets and found about 62 potentially
habitable planets. "This number could have been very, very small,'' said
Caltech astronomer Courtney Dressing. "I, for one, am ecstatic.''