photo: nasa.gov - Kepler Spacecraft
Since its launch in March 2009, Kepler telescope US space agency (NASA) to scan the sky, to search for Earth-like planets orbiting other stars.
So far there are more than 1,000 exoplanets were successfully scanned the productive telescope.
More recently, the results of the detection of Kepler, astronomers found 8 exoplanets, or planets outside our solar system that might sustain life. Two of them even has similarities with Earth.
The eight planets orbiting in the habitable zone of their star. Or within a range that allows the liquid in the surface. The size is relatively small, not a giant.
"Most of these plenet probably composed of rock like Earth," said study author Guillermo Torres of the Harvard-Smithsonian Center for Astrophysics (CfA) in a statement, as quoted from the site SPACE.com science, Wednesday (07/01/2015).
The results of the Kepler detection dikonfimasi other telescope observations and computer programs that assess the statistical probability that they are bona fide. Not fake.
Although no one in the category of "alien Earth" or alien earth - two of them, namely Kepler and Kepler-438b-442b has in common with the human planet. Although both dwarf star orbiting a smaller and dimmer than the sun.
Kepler-438b, a distance of 470 light years from our solar system, only 12 percent wider than Earth and have a chance of 70 percent is composed of rocks. Once orbits its star, the planet spent 35 days, and receive 40 percent more energy than that received by the Earth from the sun.
Meanwhile, the size of the Kepler-442b about a third larger than the Earth. The chances are composed of rocks of about 60 percent. Once orbits its star, he spent 112 days. He got two-thirds of the Earth's energy received from the sun. According to scientists, the distance is about 1,100 light years from Earth.
Although similar to Earth, scientists emphasize, there is not necessarily in the second life of the planet.
"We do not know for sure if one of the planets in our sample truly livable," said another writer, David Kipping, also from the CFA. "At least they are a candidate."
Many things that are uncertain. Including the composition of the planet. Though the planet's surface temperature depends on the composition and thickness of the atmosphere. Also does anyone know for sure about the air around Kepler and Kepler-438b-442b.
And some scientists use a stricter definition about the "habitable zone". Study team member Douglas Caldwell said, it is only 3 of 8 confirmed planet in the habitable zone. However, the team did not overlook the possibility of a potentially habitable 5 other living beings.
Only 1,000 alien planet that is identified as a potential planet by Kepler are officially confirmed. And 90 percent of them validated.
Of the 554 new candidates are announced, 8 of which are relatively small - between 1 and 2 times the size of Earth and orbit in the habitable zone of its star. Six of 8 orbiting the star belongs to the sun.
"Candidates that represents the Earth and the Sun system analogy," said Fergal Mullally of Kepler Science Office. "That's what actually sought by Kepler. We are getting closer to the discovery of a twin Earth orbiting around other stars."
