NASA's Kepler Telescope Discovers First Earth-Size Planet in 'Habitable Zone'

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NASA's Kepler Telescope Discovers First Earth-Size Planet in

'Habitable Zone'

WASHINGTON, April 17, 2014 /PRNewswire-USNewswire/ -- Using NASA's

Kepler Space Telescope, astronomers have discovered the first

Earth-size planet orbiting a star in the "habitable zone" -- the range

of distance from a star where liquid water might pool on the surface

of an orbiting planet. The discovery of Kepler-186f confirms that

planets the size of Earth exist in the habitable zone of stars other

than our sun.

While planets have previously been found in the habitable zone, they

are all at least 40 percent larger in size than Earth and

understanding their makeup is challenging. Kepler-186f is more

reminiscent of Earth.

"The discovery of Kepler-186f is a significant step toward finding

worlds like our planet Earth," said Paul Hertz, NASA's Astrophysics

Division director at the agency's headquarters in Washington. "Future

NASA missions, like the Transiting Exoplanet Survey Satellite and the

James Webb Space Telescope, will discover the nearest rocky exoplanets

and determine their composition and atmospheric conditions, continuing

humankind's quest to find truly Earth-like worlds."

Although the size of Kepler-186f is known, its mass and composition

are not. Previous research, however, suggests that a planet the size

of Kepler-186f is likely to be rocky.

"We know of just one planet where life exists -- Earth. When we search

for life outside our solar system we focus on finding planets with

characteristics that mimic that of Earth," said Elisa Quintana,

research scientist at the SETI Institute at NASA's Ames Research

Center in Moffett Field, Calif., and lead author of the paper

published today in the journal Science. "Finding a habitable zone

planet comparable to Earth in size is a major step forward."

Kepler-186f resides in the Kepler-186 system, about 500 light-years

from Earth in the constellation Cygnus. The system is also home to

four companion planets, which orbit a star half the size and mass of

our sun. The star is classified as an M dwarf, or red dwarf, a class

of stars that makes up 70 percent of the stars in the Milky Way

galaxy.

"M dwarfs are the most numerous stars," said Quintana. "The first

signs of other life in the galaxy may well come from planets orbiting

an M dwarf."

Kepler-186f orbits its star once every 130-days and receives one-third

the energy from its star that Earth gets from the sun, placing it

nearer the outer edge of the habitable zone. On the surface of

Kepler-186f, the brightness of its star at high noon is only as bright

as our sun appears to us about an hour before sunset.

"Being in the habitable zone does not mean we know this planet is

habitable. The temperature on the planet is strongly dependent on what

kind of atmosphere the planet has," said Thomas Barclay, research

scientist at the Bay Area Environmental Research Institute at Ames,

and co-author of the paper. "Kepler-186f can be thought of as an

Earth-cousin rather than an Earth-twin. It has many properties that

resemble Earth."

The four companion planets, Kepler-186b, Kepler-186c, Kepler-186d, and

Kepler-186e, whiz around their sun every four, seven, 13, and 22 days,

respectively, making them too hot for life as we know it. These four

inner planets all measure less than 1.5 times the size of Earth.

The next steps in the search for distant life include looking for true

Earth-twins -- Earth-size planets orbiting within the habitable zone

of a sun-like star -- and measuring the their chemical compositions.

The Kepler Space Telescope, which simultaneously and continuously

measured the brightness of more than 150,000 stars, is NASA's first

mission capable of detecting Earth-size planets around stars like our

sun.

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.

The SETI Institute is a private, nonprofit organization dedicated to

scientific research, education and public outreach. The mission of

the SETI Institute is to explore, understand and explain the origin,

nature and prevalence of life in the universe.

For more information about the Kepler mission, visit:

http://www.nasa.gov/kepler

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SOURCE NASA

-0- 04/17/2014

/CONTACT: J.D. Harrington, Headquarters, Washington, 202-358-5241, j.d.harrington@nasa.gov; Michele Johnson, Ames Research Center, Moffett Field, Calif., 650-604-4789, michele.johnson@nasa.gov; Karen Randall, SETI Institute, 650 960-4537, krandall@seti.org

/Photo: http://photos.prnewswire.com/prnh/20081007/38461LOGO

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/Web Site: http://www.nasa.gov

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