Credit: NASA Ames/SETI Institute/JPL-CalTech
Kepler Space Telescope was launched in spring of 2009 and it has been hunting exoplanets ever since. Recently Kepler Space Telescope found an Earth-twin (Kepler-186f); a planet that is essentially like ours in terms of composition, habitability and size. Kepler has recently confirmed the discovery of an exactly Earth-sized exoplanet and this exoplanet is also in its star’s habitable zone. This announcement was made at a press conference. The findings have also been published in Science.
Life as we know it needs the presence of liquid water and a planet in order to support life would not be too close to its parent star (which would be too hot and the water would be vaporize in a short period of time) yet not too far away from its parent star (where it would be too cold and the water would be frozen). Habitability on a planet requires a “Goldilocks Zone” where conditions are just accurate to support life.
"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, lead author of the paper. "Finding a habitable zone planet comparable to Earth in size is a major step forward."
Kepler-186f is nearly around 10% larger than Earth. Kepler-186f orbits an M dwarf star, which is around 500 light-years away in the constellation Cygnus. The parent star of Kepler-186f is about half of the mass and the size of our sun. Kepler-186f takes about 130 Earth days to complete a revolution. On the outer edge of the star’s habitable zone, the planet gets about a third of the radiation from its parent star just like we do from ours.
In order to determine the composition of planets out in the habitable zone using current technology isn’t as easy as those who are extremely close to the star, because there isn’t as much radiation from the star accessible to decide what is or isn’t getting absorbed. Although previous discoveries have showed that Kepler-186f is a rocky planet, more analysis must be done in order to reach any definitive conclusions.
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