Astronomers have found three planets orbiting far-off stars that are close to Earth-sized and in the "habitable zone": a distance from their suns that makes the planets' surfaces neither too hot nor too cold, but just right.
One of the three planets orbits a star with the prosaic name Kepler-69. "Kepler-69 is a sun-like star," says , a research scientist at the Bay Area Environmental Research Institute who uses the , which is on a mission to search for Earth-like planets.
It finds planets by looking for tiny dips in the light coming from a star. The dips come when a planet passes in front of a star. By measuring the interval between dips, astronomers can figure out how long it takes a planet to orbit its star.
The planet around Kepler-69 is "around 70 percent bigger than Earth, so what we call super-Earth-sized," says Barclay. "This represents the first super-Earth-sized planet in the habitable zone of a star like our sun."
Twenty five years ago, if you had asked astronomers if there were planets around other stars, they'd probably say maybe, but they'd admit they were just speculating.