Earth-Size Planet Found In The 'Habitable Zone' of Another Star
 
April 17, 2014: Using NASA's Kepler Space Telescope, astronomers have
discovered the first Earth-size planet orbiting in the "habitable zone" of
another star. The planet, named "Kepler-186f" orbits an M dwarf, or red dwarf,
a class of stars that makes up 70 percent of the stars in the Milky Way
galaxy. The discovery of Kepler-186f confirms that planets the size of Earth
exist in the habitable zone of stars other than our sun.
 
The "habitable zone" is defined as the range of distances from a star where
liquid water might pool on the surface of an orbiting planet. While planets
have previously been found in the habitable zone, the previous finds are all
at least 40 percent larger in size than Earth and understanding their makeup
is challenging. Kepler-186f is more reminiscent of Earth.
 
http://tinyurl.com/p9z7kkv
 
The artist's concept depicts Kepler-186f , the first validated Earth-size
planet to orbit a distant star in the habitable zone.  More
 
Kepler-186f orbits its parent M dwarf star once every 130-days and receives
one-third the energy 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.
 
"M dwarfs are the most numerous stars," 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. "The first signs of other life in the galaxy may well come from
planets orbiting an M dwarf."
 
However, "being in the habitable zone does not mean we know this planet is
habitable," cautions Thomas Barclay, a research scientist at the Bay Area
Environmental Research Institute at Ames, and co-author of the paper. "The
temperature on the planet is strongly dependent on what kind of atmosphere the
planet has. Kepler-186f can be thought of as an Earth-cousin rather than an
Earth-twin. It has many properties that resemble Earth."
 
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: 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.
 
http://tinyurl.com/ockqtns
 
The diagram compares the planets of our inner solar system to Kepler-186, a
five-planet star system about 500 light-years from Earth in the constellation
Cygnus.  More
 
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.
 
"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.
 
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.
 
Looking ahead, Hertz said, "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."
 
Credits:
Production editor: Dr. Tony Phillips | Credit: Science@NASA
 
More information:
 
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
 
 
Regards,
 
Roger

--- D'Bridge 3.99
 * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)