Two of the newly discovered rocky planets spotted by the Kepler space telescope could be habitable, scientists said.
NASA's Kepler space telescope recently discovered 104 exoplanets, including four possibly rocky planets circling a red dwarf star called K2-72, which was found to be smaller and dimmer than the solar system's sun, 181 light-years from Earth in the Aquarius constellation.
According to the discovery team, the four worlds are about 20 percent to 50 percent wider than the Earth and are likely "rocky."
Two of these four rocky planets, which are known as K2-72c and K2-72e, appear to be located in the star's "habitable zone," which might be in the range of distance where liquid water could exist on the world's surface, scientists said in a news release.
According to scientists, these planets are closer to their star than Mercury is to the sun. But because the red dwarf is smaller and cooler, the habitable zone is much closer.
For example, K2-72c has a "year" about 15 Earth-days long, which is the time it takes to complete one orbit. This planet could be about 10 percent warmer than the Earth, scientists said.
For K2-72e, a year could last 24 Earth days, and because it is more distant, it could be about 6 percent cooler than Earth.
Kepler discovered the alien planets when it spotted the tiny brightness dips they caused when they crossed the faces of their host stars from the spacecraft's perspective.
After losing the second of its four orientation-maintaining reaction wheels in May 2013, Kepler team members only recently discovered a way to stabilize the telescope using sunlight pressure and the remaining wheels.
It was finally able to embark on the K2 mission in 2014, where it observed a variety of cosmic phenomena, including the 104 exoplanets.
The Kepler space telescope has now discovered over 2,300 alien planets since its launch in March 2009. According to a report by Space.com, over 2,000 Kepler "candidates" await further investigation.