The European Southern Observatory (ESO) this week announced it has found six planets in the Gliese 667C system, and that three of those planets are located within the system’s habitable zone. The habitable zone of a system is the area around a star where liquid water can exist. With the presence of water also comes the possibility for life as we know it.

Gliese 667C is smaller than the Sun and is just 22 light-years away from earth. It is part of the greater triple star system known as Gliese 667. The three exoplanets are so-called “super-Earths” – planets more massive than Earth, but still rocky. This is the first time three planets have been found in the habitable zone of a star other than the Sun. Venus, Earth, and Mars are all within the habitable zone of our solar system.

“We knew that the star had three planets from previous studies, so we wanted to see whether there were any more,” said Mikko Tuomi, an astronomer at the University of Hertfordshire. “By adding some new observations and revisiting existing data we were able to confirm these three and confidently reveal several more. Finding three low-mass planets in the star’s habitable zone is very exciting!”

Previous studies of Gliese 667C had found only three planets, with one being in the star’s habitable zone. The new planets were found by combining data from HARPS, the ESO’s Very Large Telescope, the W.M. Keck Observatory, and the Magellan Telescope.

“The number of potentially habitable planets in our galaxy is much greater if we can expect to find several of them around each low-mass star – instead of looking at ten stars to look for a single potentially habitable planet, we now know we can look at just one star and find several of them,” said Rory Barnes, co-author of the study and an astronomer at the University of Washington.

(Image courtesy ESO/M. Kornmesser)