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MOFFET
FIELD, California (Reuters) - The most Earth-like planet ever
discovered is circling a star 600 light years away, a key finding in an
ongoing quest to learn if life exists beyond Earth, scientists said on
Monday.
The planet, called Kepler-22b, joins a list of more than 500 planets
found to orbit stars beyond our solar system. It is the smallest and the
best positioned to have liquid water on its surface -- among the
ingredients necessary for life on Earth.
"We are homing in on the true Earth-sized, habitable planets," said
San Jose State University astronomer Natalie Batalha, deputy science
team lead for NASA's Kepler Space Telescope that discovered the star.
The telescope, which was launched three years ago, is staring at
about 150,000 stars in the constellations Cygnus and Lyra, looking for
faint and periodic dimming as any circling planets pass by, relative to
Kepler's line of sight.
Results will be extrapolated to determine the percentage of stars in
the Milky Way galaxy that harbor potentially habitable, Earth-size
planets.
This is the first detection of a potentially habitable world orbiting
a Sun-like star, scientists reported in findings to be published in The
Astrophysical Journal.
Kepler-22b is 600 light years away. A light year is the distance
light travels in a year, about 6 trillion miles (10 trillion km).
GROUND TELESCOPES
Planets about the same distance from their parent stars as Earth take
roughly a year to complete an orbit. Scientists want to see at least
three transits to be able to rule out other explanations for
fluctuations in a star's light, such as small companion stars. Results
also are verified by ground and other space telescopes.
Kepler-22b, which is about 2.4 times the radius of Earth, sits
squarely in its star's so-called "habitable zone," the region where
liquid water could exist on the surface. Follow-up studies are under way
to determine if the planet is solid, like Earth, or more gaseous like
Neptune.
"We don't know anything about the planets between Earth-size and
Neptune-size because in our solar system we have no examples of such
planets. We don't know what fraction are going to be rocky, what
fraction are going to be water worlds, what fraction are ice worlds. We
have no idea until we measure one and see," Batalha said at a news
conference at NASA Ames Research Center in Moffet Field, California.
If Kepler-22b has a surface and a cushion of atmosphere similar to
Earth's, it would be about 72 degrees Fahrenheit (22 C), about the same
as a spring day in Earth's temperate zone.
Among the 2,326 candidate planets found by the Kepler team, 10 are
roughly Earth-size and reside in their host stars' habitable zones.
Another team of privately funded astronomers is scanning the target
stars for non-naturally occurring radio signals, part of a project known
as SETI, or the Search for Extraterrestrial Intelligence.
"As soon as we find a different, a separate, an independent example
of life somewhere else, we're going to know that it's ubiquitous
throughout the universe," said astronomer Jill Tarter, director of the
SETI Institute in Mountain View.
The Kepler team is meeting for its first science conference this week.
(Additional reporting by Debby Zabarenko in Washington; Editing by Jane Sutton and Philip Barbara)
Enlarge PhotoHandout picture of an artist's illustration of Kepler-22b
MOFFET
FIELD, California (Reuters) - The most Earth-like planet ever
discovered is circling a star 600 light years away, a key finding in an
ongoing quest to learn if life exists beyond Earth, scientists said on
Monday.
The planet, called Kepler-22b, joins a list of more than 500 planets
found to orbit stars beyond our solar system. It is the smallest and the
best positioned to have liquid water on its surface -- among the
ingredients necessary for life on Earth.
"We are homing in on the true Earth-sized, habitable planets," said
San Jose State University astronomer Natalie Batalha, deputy science
team lead for NASA's Kepler Space Telescope that discovered the star.
The telescope, which was launched three years ago, is staring at
about 150,000 stars in the constellations Cygnus and Lyra, looking for
faint and periodic dimming as any circling planets pass by, relative to
Kepler's line of sight.
Results will be extrapolated to determine the percentage of stars in
the Milky Way galaxy that harbor potentially habitable, Earth-size
planets.
This is the first detection of a potentially habitable world orbiting
a Sun-like star, scientists reported in findings to be published in The
Astrophysical Journal.
Kepler-22b is 600 light years away. A light year is the distance
light travels in a year, about 6 trillion miles (10 trillion km).
GROUND TELESCOPES
Planets about the same distance from their parent stars as Earth take
roughly a year to complete an orbit. Scientists want to see at least
three transits to be able to rule out other explanations for
fluctuations in a star's light, such as small companion stars. Results
also are verified by ground and other space telescopes.
Kepler-22b, which is about 2.4 times the radius of Earth, sits
squarely in its star's so-called "habitable zone," the region where
liquid water could exist on the surface. Follow-up studies are under way
to determine if the planet is solid, like Earth, or more gaseous like
Neptune.
"We don't know anything about the planets between Earth-size and
Neptune-size because in our solar system we have no examples of such
planets. We don't know what fraction are going to be rocky, what
fraction are going to be water worlds, what fraction are ice worlds. We
have no idea until we measure one and see," Batalha said at a news
conference at NASA Ames Research Center in Moffet Field, California.
If Kepler-22b has a surface and a cushion of atmosphere similar to
Earth's, it would be about 72 degrees Fahrenheit (22 C), about the same
as a spring day in Earth's temperate zone.
Among the 2,326 candidate planets found by the Kepler team, 10 are
roughly Earth-size and reside in their host stars' habitable zones.
Another team of privately funded astronomers is scanning the target
stars for non-naturally occurring radio signals, part of a project known
as SETI, or the Search for Extraterrestrial Intelligence.
"As soon as we find a different, a separate, an independent example
of life somewhere else, we're going to know that it's ubiquitous
throughout the universe," said astronomer Jill Tarter, director of the
SETI Institute in Mountain View.
The Kepler team is meeting for its first science conference this week.
(Additional reporting by Debby Zabarenko in Washington; Editing by Jane Sutton and Philip Barbara)