"This planet doesn't have days and nights. Wherever you are on this planet, the sun is in the same position all the time. You have very stable zones where the ecosystem stays the same temperature... basically forever," Vogt said. "If life can evolve, it's going to have billions and billions of years to adapt to the surface."
"Given the ubiquity of water, it seems probable that this thing actually has liquid water. On the surface of the Earth, everywhere you have liquid water you have life," Vogt added.
The question wouldn't be to defend that there is life at Gliese 581g, says Butler. "The question," he said, "would be to demonstrate that there isn't."
Current technologies won't allow scientists to study the planet's atmosphere for chemical signs of life, but astronomers expect many more similar life-friendly planets to be discovered soon. If one or more of those cross the face of their parent star, relative to our line of sight, then it's possible to gather atmospheric data.
"This system is not in an orientation such that this planet would ever transit, so unfortunately this is not a case where nature has thrown us a bone," Vogt noted. "That being said, it is so close and we have found this thing so soon that it suggests we will start finding a lot of these things in the future and eventually we will find systems that do transit. This is a harbinger of things to come."