NASA's Kepler Discovers Its Smallest 'Habitable Zone' Planets to Date
Relative sizes of all of the habitable-zone planets discovered to date
alongside Earth. Left to right: Kepler-22b, Kepler-69c, Kepler-62e,
Kepler-62f and Earth (except for Earth, these are artists' renditions).
Image credit: NASA Ames/JPL-Caltech.
MOFFETT FIELD, Calif. -- NASA's Kepler mission has discovered two new
planetary systems that include three super-Earth-size planets in the
"habitable zone," the range of distance from a star where the surface
temperature of an orbiting planet might be suitable for liquid water.
The Kepler-62 system has five planets; 62b, 62c, 62d, 62e and 62f. The
Kepler-69 system has two planets; 69b and 69c. Kepler-62e, 62f and 69c
are the super-Earth-sized planets.
Two of the newly discovered planets orbit a star smaller and cooler than
the sun. Kepler-62f is only 40 percent larger than Earth, making it the
exoplanet closest to the size of our planet known in the habitable zone
of another star. Kepler-62f is likely to have a rocky composition.
Kepler-62e, orbits on the inner edge of the habitable zone and is
roughly 60 percent larger than Earth.
The third planet, Kepler-69c, is 70 percent larger than the size of
Earth, and orbits in the habitable zone of a star similar to our sun.
Astronomers are uncertain about the composition of Kepler-69c, but its
orbit of 242 days around a sun-like star resembles that of our
neighboring planet Venus.
Scientists do not know whether life could exist on the newfound planets,
but their discovery signals we are another step closer to finding a
world similar to Earth around a star like our sun.
"The Kepler spacecraft has certainly turned out to be a rock star of
science," said John Grunsfeld, associate administrator of the Science
Mission Directorate at NASA Headquarters in Washington. "The discovery
of these rocky planets in the habitable zone brings us a bit closer to
finding a place like home. It is only a matter of time before we know if
the galaxy is home to a multitude of planets like Earth, or if we are a
rarity."
The Kepler space telescope, which simultaneously and continuously
measures the brightness of more than 150,000 stars, is NASA's first
mission capable of detecting Earth-size planets around stars like our
sun.
Orbiting its star every 122 days, Kepler-62e was the first of these
habitable zone planets identified. Kepler-62f, with an orbital period of
267 days, was later found by Eric Agol, associate professor of
astronomy at the University of Washington and co-author of a paper on
the discoveries published in the journal Science.
The size of Kepler-62f is now measured, but its mass and composition are
not. However, based on previous studies of rocky exoplanets similar in
size, scientists are able to estimate its mass by association.
"The detection and confirmation of planets is an enormously
collaborative effort of talent and resources, and requires expertise
from across the scientific community to produce these tremendous
results," said William Borucki, Kepler science principal investigator at
NASA's Ames Research Center at Moffett Field, Calif., and lead author
of the Kepler-62 system paper in Science. "Kepler has brought a
resurgence of astronomical discoveries and we are making excellent
progress toward determining if planets like ours are the exception or
the rule."
The two habitable zone worlds orbiting Kepler-62 have three companions
in orbits closer to their star, two larger than the size of Earth and
one about the size of Mars. Kepler-62b, Kepler-62c and Kepler-62d, orbit
every five, 12, and 18 days, respectively, making them very hot and
inhospitable for life as we know it.
The five planets of the Kepler-62 system orbit a star classified as a K2
dwarf, measuring just two-thirds the size of the sun and only one-fifth
as bright. At seven billion years old, the star is somewhat older than
the sun. It is about 1,200 light-years from Earth in the constellation
Lyra.
A companion to Kepler-69c, known as Kepler-69b, is more than twice the
size of Earth and whizzes around its star every 13 days. The Kepler-69
planets' host star belongs to the same class as our sun, called G-type.
It is 93 percent the size of the sun and 80 percent as luminous and is
located approximately 2,700 light-years from Earth in the constellation
Cygnus.
"We only know of one star that hosts a planet with life, the sun.
Finding a planet in the habitable zone around a star like our sun is a
significant milestone toward finding truly Earth-like planets," said
Thomas Barclay, Kepler scientist at the Bay Area Environmental Research
Institute in Sonoma, Calif., and lead author of the Kepler-69 system
discovery published in the Astrophysical Journal.
When a planet candidate transits, or passes in front of the star from
the spacecraft's vantage point, a percentage of light from the star is
blocked. The resulting dip in the brightness of the starlight reveals
the transiting planet's size relative to its star. Using the transit
method, Kepler has detected 2,740 candidates. Using various analysis
techniques, ground telescopes and other space assets, 122 planets have
been confirmed.
Early in the mission, the Kepler telescope primarily found large,
gaseous giants in very close orbits of their stars. Known as "hot
Jupiters," these are easier to detect due to their size and very short
orbital periods. Earth would take three years to accomplish the three
transits required to be accepted as a planet candidate. As Kepler
continues to observe, transit signals of habitable zone planets the size
of Earth orbiting stars like the sun will begin to emerge.
Ames is responsible for Kepler's ground system development, mission
operations, and science data analysis. NASA's Jet Propulsion Laboratory
in Pasadena, Calif., managed Kepler mission development.
Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the
Kepler flight system and supports mission operations with the
Laboratory for Atmospheric and Space Physics at the University of
Colorado in Boulder.
The Space Telescope Science Institute in Baltimore archives, hosts and
distributes Kepler science data. Kepler is NASA's 10th Discovery Mission
and was funded by the agency's Science Mission Directorate.
For more information about the Kepler mission and to view the digital press kit, visit:
http://www.nasa.gov/kepler
Video: Kepler Discovers its Smallest 'Habitable Zone' Planets to Date
Click here to go to a site with downloadable video.
Text issued as NASA release 13-112 and NASA Ames release 13-31AR
Michele Johnson
Ames Research Center, Moffett Field, Calif.
650-604-6982
michele.johnson@nasa.gov
J.D. Harrington
Headquarters, Washington
202-358-5241
j.d.harrington@nasa.gov
NASA Hosts Kepler Spacecraft Status Teleconference Today
05.15.2013
MOFFETT FIELD, Calif. -- NASA will host a news teleconference at 4 p.m.
EDT, today, May 15, to discuss the status of the agency's Kepler Space
Telescope.
Kepler is the first NASA mission capable of finding Earth-size planets
in or near the habitable zone, which is the range of distance from a
star where the surface temperature of an orbiting planet might be
suitable for liquid water. Launched in 2009, Kepler has been detecting
planets and planet candidates with a wide range of sizes and orbital
distances to help scientists better understand our place in the galaxy.
The briefing participants are:
-- John Grunsfeld, associate administrator, Science Mission Directorate, NASA Headquarters, Washington
-- Paul Hertz, astrophysics director, NASA Headquarters, Washington
-- William Borucki, Kepler science principal investigator, NASA's Ames Research Center, Calif.
-- Charles Sobeck, deputy project manager, NASA's Ames Research Center, Calif.
For dial-in information, journalists should e-mail their name, affiliation and telephone number to J.D. Harrington at
j.d.harrington@nasa.gov. Media representatives and the public also can questions via Twitter to #AskNASA.
Audio of the teleconference will be streamed live on NASA's website at:
http://www.nasa.gov/newsaudio
For more information about the Kepler mission, visit:
NASA
Guillermo Gonzalo Sanchez Achutegui
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ayabaca@hotmail.com
ayabaca@yahoo.com
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Image above: Kepler's targeted star field graphic. Credit: NASA 
