Astronomers on 17 April 2014 announced that they have discovered an Earth-size planet, named Kepler-186f. The planet is located in the habitable zone—a range of distance from a star where liquid water might pool on the planet's surface. It is a part of the Kepler-186 system, which is located about 500 light-years from Earth in the constellation Cygnus.
This Kepler-186f also called as the Earth cousin, orbits around a red dwarf (M dwarf), which is a type of star much smaller and dimmer than Earth’s sun. Our galaxy has about 100 billion stars of which seven out of every ten of them are M dwarfs.
The astronomers have claimed that discovery of Kepler-186f has confirmed that Earth-size planets actually exist in the habitable zones of other stars. This also signals a significant step closer to find a world similar to earth.
Size and the period of orbiting the star by Kepler-186f
• The astronomers claimed that the exoplanet is known to be less than 10% larger than Earth but they doesn’t know about its mass, composition and density. The previous study suggests that a planet size of discovered Kepler-186f is rocky.
• It orbits its star in 130 days and it receives one-third energy from its star as Earth receives from our sun.
• The Kepler-186 system’s star is half in size and mass of the sun and is a home of four inner planets
Prior to the discovery of Kepler-186f, a similar Earth-like planet was Kepler-62f that was 40% larger than the size of Earth and it also orbited its star in habitable zone. Kepler-186f is a tip-of-the-iceberg discovery.
Elisa Quintana is the Study leader and is a planetary scientist at NASA Ames Research Center at Moffett Field