There’s good news for people hoping that Earth is not the only inhabited world in the universe. A team of astronomers announced on January 6 that they have identified eight planets beyond our solar system. The scientists say three or four of those planets orbit in their stars’ “Goldilocks Zone”—the region where temperatures are not too hot and not too cold for water to exist in liquid form. Water is a necessary ingredient for life as we know it.
The scientists, led by Dr. Guillermo Torres of the Harvard-Smithsonian Center for Astrophysics, made the discoveries using data collected by the planet-seeking Kepler telescope.
Eye on the Stars
NASA launched Kepler in 2009. Since then, the telescope has identified more than 1,000 planets outside of our solar system. Torres and his team analyzed the data about the eight newly discovered worlds to determine which ones are most likely to be similar to Earth.
Among the new discoveries, the scientists say the planets called Kepler 438b and 442b are the closest to Earth. Kepler 438b is just about 10% larger than our planet, and gets 40% more of its energy from its star than Earth receives from the Sun. Temperatures there would be about 140 degrees. Kepler 442b is about 33% larger than Earth, but receives 30% less energy from its star. That would make it a potentially chillier world than our own. Torres says it is possible for life to exist and survive in either of those temperatures. But for that to happen, these planets would need to have another key ingredient for life: a heat-trapping atmosphere like Earth’s.
A Lot Left to Learn
While these findings add to the possibility that life exists beyond Earth, Torres cautions against drawing conclusions. “We’re not claiming they’re inhabited,” he says. In fact, these planets are so far away that scientists cannot observe them directly. For now, it remains unknown whether these planets contain life. But the discovery of planets in their stars’ habitable zones suggests that somewhere out there, some form of alien life may have taken hold.
Reporting by Michael Lemonick for TIME and AP.