Posted by jlwile on October 16, 2010
Not too long ago, a commenter asked about a “Goldilocks Planet” that had recently been discovered by Steven Vogt and his colleagues. The term refers to a planet that is thought to be close enough to its star to be warm, but not so close that it is unbearably hot. In other words, it is supposed to have a temperature that is “just right” for the existence of life.
Steven Vogt and his colleagues thought they had found such a planet in Gliese 581g. It is supposed to orbit a red dwarf (Gliese 581) with a period of 37 days. While this puts it very close to its star, Vogt and his team think it is hospitable to life because the red dwarf is cool compared to the sun.
In response to the commenter, I expressed my skepticism, not because I have a problem with the idea of extraterrestrial life, but because astronomers have been wrong in their assignment of “Goldilocks” status before. In addition, even if the planet is at the right distance from its star, there are a host of other conditions necessary for a planet to be hospitable to life.
Well, now there is another reason to be skeptical. The planet may not exist!
Planets outside our solar system are not usually observed directly. Instead, they are found because they cause the star they orbit to ‘wobble.’ The wobble in the star’s motion can be analyzed, and from those data, certain characteristics of the planet can be deduced. Using this method, four planets had been discovered orbiting Gliese 581 (planets b- e), but Vogt and his colleagues claim to have found two more, one of which is the “Goldilocks Planet” (planet g). At an International Astronomical Union symposium in Italy, however, another team of astronomers led by Francesco Pepe analyzed more data on the star’s motion, and they say they cannot find evidence for either of the planets that Vogt’s team found.
Why the discrepancy between the two groups? Well, the ‘wobbles’ produced by the planets are small, and it takes a lot of observations to make sure what you interpret as a ‘wobble’ isn’t just random noise. Vogt’s team thought they had distinguished the wobbles from the noise, but Pepe’s team couldn’t find them.
Who’s right? It is hard to say, but my bet is that Pepe’s team is right, since they are working with more data. Regardless of who is right, however, this story illustrates how skeptical you should be when it comes to stories about new scientific discoveries. Despite the fact that some news agencies breathlessly reported the exciting discovery of another planet that might support life, it turns out that the planet itself might not even exist!