Not Quite a Blog

Link: http://sciencenow.sciencemag.org/cgi/content/full/2004/825/1?etoc

(You or your institution will have to have a subscription to Science to click through the link above.)

When it comes to extrasolar planets, smaller is better--at least for astronomers, who long to find worlds like Earth. A European team now has taken a step toward that goal by spotting the smallest planet yet found circling an ordinary star. The planet weighs in at 14 times Earth's mass, and although the astronomers have no direct evidence of the planet's composition, it may be the first known alien world made mainly of rock, rather than gas, in a planetary system like our sun's.

[...]

The planet races around µ Arae at less than 1/10th of the distance between Earth and the sun. According to models of planetary formation, an object of that size is too small to have coalesced farther out as a gas giant and then migrated toward the star. Rather, Santos says, it probably formed near its present orbit by accumulating a hot core of rock and a relatively small gaseous atmosphere.

Because the planet does not cross directly in front of its star, the team cannot confirm its inferences by measuring the planet's radius, says planetary theorist Alan Boss of the Carnegie Institution of Washington in Washington, D.C. Still, Boss finds the logic convincing: "They seem to have found what I would call the top end of the range of terrestrial-type planets. This is a very encouraging sign that we will find a lot of lower-mass rocky planets in the next 10 years or so."

This is wicked. We'll find many more like this in the coming decade (by 2010). I expect the announcement of an Earth-sized planet areound a Sun-like star to be within the year (end of 2004). I also expect the same but in an Earth-like orbit will be found within three years (September of 2007).