NASA’s Kepler mission has identified Kepler-186f, the first Earth-sized planet discovered in a distant star’s habitable zone, a key milestone in the search for alien life.
Earth’s Twin? New Planet Found in Habitable Zone by NASA’s Kepler Telescope
Astronomers have confirmed an exciting discovery that has stirred the scientific community—an Earth-sized planet has been found orbiting a distant star in what scientists call the “habitable zone,” the region around a star where liquid water could potentially exist on a planet’s surface.
This planet, named Kepler-186f, was detected by NASA’s Kepler Space Telescope and lies approximately 500 light-years away from Earth in the constellation Cygnus. It marks a significant milestone: the first Earth-sized planet confirmed to orbit within the habitable zone of a star outside our solar system.
The “habitable zone,” also known as the Goldilocks zone, is the range of distances from a star where temperatures are just right—not too hot and not too cold—for liquid water to exist, given sufficient atmospheric pressure. Liquid water is considered one of the key ingredients for life as we know it.
While astronomers estimate there are over 40 billion Earth-sized planets in the Milky Way galaxy, Kepler-186f is unique because it is the first to meet both critical criteria: similar size to Earth and location within a star’s habitable zone.
“This discovery is a major step forward in our quest to find life beyond Earth,” said Elisa Quintana, a research scientist at the SETI Institute and NASA’s Ames Research Center in California. Quintana, who also led the study published in the journal Science, explained, “Earth is the only planet we know of that harbors life. So when searching for life beyond our solar system, we focus on planets with Earth-like characteristics.”
Kepler-186f orbits a star that is about half the mass and size of our Sun and receives only about one-third of the sunlight that Earth gets. Its orbit takes about 130 days to complete, placing it close enough to its star to be warm, but far enough to potentially avoid excessive heat. Although scientists have not confirmed whether Kepler-186f has an atmosphere or liquid water, its size and orbital location make it a compelling candidate for further study in the search for potentially habitable worlds.
