Of those possible planets, eight are in the so-called "Goldilocks zone," or habitable zone, where the host star is at just the right distance to keep water liquid. Too close, and water heats up and boils off. Too far, and the planet is covered in permanent, solid ice.
These findings nearly double the number of known planets in the habitable zone, but researchers are especially excited about two of the new exoplanets: Their size, location, and star type means they could be rocky planets like Earth -- which means they could have evolved life as we recognize it.
One of the planets, Kepler-438b, is only 12 percent bigger than Earth in diameter. That means it's quite likely a rocky planet. Scientists have given it a 70 percent chance. Kepler-442b is a bit bigger at around 33 percent larger than Earth, but still has a 60 percent chance of being rocky.
But while 438b hits the sweet spot in size, 442b has it beat when it comes to distance from the sun. Both planets orbit a small red dwarf star, cooler than Earth's Sun, but they also orbit more closely. 438b gets 40 percent more light than Earth, which means it has around a 70 percent chance of being able to hold liquid water. But with 66 percent as much light as our own planet, 442b has a 97 percent chance of being in the habitable zone.
'We are now closer than we’ve ever been to finding a twin for the Earth around another star," NASA scientist Fergal Mullally said while introducing his portion of the research at the conference Tuesday. He and his colleagues hope to verify these planets for further study, then use their similarities to -- and differences from -- Earth to learn something about the formation of the planet.