Scientists need at least three transits -- plus follow-up observations by ground-based telescopes -- before an extrasolar planet is confirmed. Since the first planet beyond the solar system was discovered in 1996, astronomers have added nearly 1,800 to the list.
"Kepler-186f is significant because it is the first exoplanet that is the same temperature and the same size (well, ALMOST!) as the Earth,” David Charbonneau, with the Harvard-Smithsonian Center for Astrophysics, wrote in an email to Discovery News.
"Previously, the exoplanet most like Earth was Kepler-62f, but Kepler-186f is significantly smaller,” Charbonneau added.
“Now we can point to a star and say, ‘There lies an Earth-like planet,’” he said.
Scientists continue to analysis archived Kepler data in hopes of finding true Earth twins. The telescope currently is sidelined by a positioning system problem.
Meanwhile, the Kepler-186 star, which hosts at least four more planets in addition to the strategically positioned and outermost 186f, will become the focus of sister science project that scans the skies for non-naturally occurring radio transmissions in a quest to find technically advanced extraterrestrial life.
The research is published in this week’s Science.