For long time, scientists have been trying to know is there any Sun-like star that hosts Earth-size planet? And if yes, then how many? Data collected by NASA‘s Kepler space telescope suggests that nearly a quarter of all Sun-like stars in our galaxy host planets 1-3 times the size of our planet Earth.
After conducting a five-year survey of nearby solar-mass stars, astronomers have collected huge data. Using those data, scientists have estimated about how many stars of this type could have Earth-size planets. After studying 166 G and K stars within 80 light-years of Earth, Andrew Howard and Geoffrey Marcy from the University of California Berkeley have determined the number, mass and orbital distance of any of the stars’ planets. This is the first estimate based on actual measurements of the fraction of stars that have Earth-size planets. However, although they extrapolated the number of that size of planets, based on the fraction of stars that host Neptune to super-Earth sized planets, they found big conflict with current models of planet formation and migration.
Using the Keck telescopes in Hawaii, Andrew Howard and Geoffrey Marcy measured the small wobble of each star from the tug of orbiting planets. And after long effort, they were able to detect close-in planets, which could be even more Earth-size planets at greater distances. And finally they revealed that 25 percent of Sun-like stars host Earths-size planets.