Wednesday, April 17, 2013

NASA's Kepler Mission discovers Earth-like-Planet

Scientists do not know whether life could exist on the new found 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 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.

The Kepler Mission of NASA 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.
Among all the planets, Kepler-62e, 62f and 69c are the super-Earth-sized planets.

The image below (artists concept) compares the planets of the inner solar system to Kepler-69, a two-planet system about 2,700 light-years away from the Earth.

The image below (artists concept) compares the planets of the inner solar system to Kepler-62, a five-planet system about 1,200 light-years from Earth. 

  • Two of the newly discovered planets orbit a star smaller and cooler than the sun. Kepler-62f is only 40 percent larger than Earth. 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. 
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.

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.

"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, California, and lead author of the Kepler-69 system discovery published in the Astrophysical Journal.

Early in the mission, the Kepler telescope primarily found large, gaseous giants in very close orbits of their stars. Known as "hot Jupiter’s," 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. 

To know more information about the Kepler mission of NASA and to view the digital press kit, please visit: NASA's Kepler Mission.

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