Astronomers declared a major milestone in the search for life outside of Earth, saying they had found the first Earth-sized planet that could be habitable. Their findings will be released Friday in Science magazine, according to previews of the article released Thursday, dpa reported. The planet in question is one of a handful of planets found through NASA's Kepler space telescope. It orbits a red dwarf star, called Kepler-186, about 500 light years away in the Cygnus constellation, also known as the Swan. "What makes this finding particularly compelling is that this Earth-sized planet, one of five orbiting this star, which is cooler than the Sun, resides in a temperate region where water could exist in liquid form," said Elisa Quintana of the Search for Extraterrestrial Intelligence (SETI) Institute. Kepler has enabled astronomers to identify about 20 planets orbiting their stars in a habitable zone. But most of the planets are too large, meaning they could have thick atmospheres of hydrogen and helium similar to those on Jupiter and Saturn. Scientists have determined that the ideal size for a habitable planet is something smaller than 1.5 times the size of Earth. The newly discovered planet, called "Kepler-186f," is estimated to have a radius about 1.1 times the radius of Earth. The team led by Quintana and Steve Howell, Kepler project scientist, confirmed their findings using high resolution images from the Gemini North and Keck II telescopes on Mauna Kea in Hawaii. More precise information about Kepler-186f's atmosphere must await the building and launch of NASA's Webb telescope. Since August 2013, the Kepler telescope has been hobbled by the failure of two of four gyroscopes that helped the craft maintain its position in space. But it has continued sending the observations it is still able to make. -- SPA 23:15 LOCAL TIME 20:15 GMT تغريد
