This exoplanet, which lies just 22 light-years from Earth, is at least 4.5 times as massive as Earth, and researchers aren't sure whether or not it's rocky. Gliese 667Cc completes one orbit around its host star in a mere 28 days, but that star is a red dwarf considerably cooler than the sun, so the exoplanet is thought to lie in the habitable zone. However, Gliese 667Cc — which was discovered with the European Southern Observatory's 3.6-meter telescope in Chile — may orbit close enough in to be baked by flares from the red dwarf.