French Astronomers have announced the discovery of an Earth-like planet orbiting the red dwarf Gliese 581. This is 20.5 light years away in the Libra constellation. They claim that the surface temperature runs between 32 and 104 degrees F (that’s 0 – 40 degrees Celsius).
“Liquid water is critical to life as we know it and because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extra-terrestrial life. On the treasure map of the Universe, one would be tempted to mark this planet with an X,” added Xavier Delfosse, a member of the team from Grenoble University, France.
A red dwarf is much cooler than our Sun, so the habitable zone of a red dwarf is much closer to its star. This planet is 14 times closer to its star than our planet is to the sun.
This is all speculative on my part (I’d appreciate an astronomer weighing in), but I have some question whether stars much smaller than our sun actually have a habitable zone. Being that close to a star – even a star as dim a red dwarf – might be too radioactive for life to develop.
The other potential problem is tidal lock. A celestial body that closely orbits another larger celestial body tends to present the same face to that larger body. The best example is the Moon. We always see one face of the Moon. If the “habitable zone” of a small star put it within tidal lock range, one side of the planet would be boiling and the other side would be frozen. That would not be conducive to life either.
Congradulations to the French team that discovered this planet! May it be the first of many.
UPDATE:
From the comments Karl Hallowell adds:
The problem with red dwarf stars is that they still have significant stellar flares. And that can be quite lethal at the distances that one needs to be to keep warm.
UV radiation isn’t a significant problem. The spectrum of a “black body” drops rapidly from the peak (Gliese 581 has a temperature of 3,478 K while the Sun has a temperature of 5785 K). Given that for the planet to be “Earth-like” in temperature, it must be receiving similar amounts of total energy from the star. Hence, it probably receives less UV than we do from the Sun. It also probably receives less visible light (usable for photosynthesis) as well.
So the background radiation environment is probably better, but the stellar flares probably make the environment extremely hazardous to most Earth life…
And Vadept:
According to the story I read on Yahoo, it IS tidally locked. That would suggest that if there is life, it probably exists in the “twilight” regions of the world.
Really, though, the great advent of “C” isn’t that they found a world that might contain life, it’s that they found an earthlike world in a habitable band of the star. This isn’t a Super Jupiter within an AU of the star.
This means, to my mind, not only is the technology to find MORE earth-like worlds there, but that, if they could find one so “easily” (after looking at a mere hundred stars), then there’s probably quite a few of these out there. If there’s quite a few of them, it’s quite likely we will find a planet with undoubtadly the right mix for life…
Thanks for the great comments.