Blogging astronomical discoveries

Via GNXP, I find that there are at least two blog posts --- here and here --- about yesterday's announcement of the first discovery of a potentially habitable planet outside our own.

One interesting aspect of the press release is that the paper itself has not yet been peer-reviewed, but is only submitted to Astronomy & Astrophysics. I don't work in a competitive research area, so I can afford to take a highly principled, dim view of rushed publicity on exciting scientific results. In reality, though, the HARPS group (the Europeans who discovered the planet) didn't have much of a choice, since they knew that their main competitors, the U.S. Carnegie-Caltech group, have been monitoring the same star. And in fact, from what I could gather in news accounts, the Carnegie-Caltech group confirmed the radial velocity detection immediately though they are skeptical about the estimates of the planetary temperature and the potential for liquid water.

The planetary temperature estimate is based on a calculation of the luminosity of the star and assumptions of the planetary albedo (how much the planet reflects the incident light) based on those of Earth and Venus. The calculation is quite straightforward, so the skepticism centers on the albedo values chosen. Let's assume that the planet is a rocky body (not a given, but theoretically favored). The albedos of Earth and Venus are 0.35 and 0.64, respectively. So, yes, if the new planet has an atmosphere, its temperature is favorable for life. The albedos of Mercury and Mars, however, are 0.11 and 0.15, so assuming a planet that looks more like these bodies would push the planetary temperature up out of the liquid water regime. The authors didn't cite in the paper any justification for the values they chose, so the estimates of the temperature of the planet are speculative only.

It's an intriguing speculation, though, and made one hell of a press release.