You may recall a few weeks ago, we wrote about the discovery
of the first "potentially life-sustaining planet" outside of our solar system, which got some astronomers so excited that one declared the chance of life on the planet to be 100%
. Of course, he may want to adjust his optimism a bit downwards as Slashdot
points us to the news that another group of astronomers are saying they can't find any trace of the planet
But at this week's Astrophysics of Planetary Systems meeting, astronomer Francesco Pepe of the Geneva Observatory and the Swiss group reported that he and his colleagues could find no reliable sign of a fifth planet in Gliese 581's habitable zone. They used only their own observations, but they expanded their published data set from what the U.S. group included in its analysis to a length of 6.5 years and 180 measurements. "We do not see any evidence for a fifth planet ... as announced by Vogt et al.," Pepe wrote Science in an e-mail from the meeting. On the other hand, "we can't prove there is no fifth planet." No one yet has the required precision in their observations to prove the absence of such a small exoplanet, he notes.
Astronomer Paul Butler, a member of the U.S. team who is at the Carnegie Institution for Science in Washington, D.C., says he can't comment on the Swiss work because he wasn't at the meeting and the data are unpublished. He notes, however, that more observations will likely be needed to solidify the existence of Gliese 581g. "I would expect that on the time scale of a year or two this should be settled."
So, perhaps before we declare it 100% likely to have life, we should make sure it actually exists.