• Exoplanets have been discovered circling some extremely old, metal-poor stars, creating interesting curiosities that might expand the theories of how planets form. These exoplanets might not harbor any kind of life... or we may want to get a bit more creative about how we envision life on other worlds. [url]
• A free-floating planet named CFBDSIR2149 is not orbiting a star, and it's only one of about two dozen or so known examples of a starless planet. This rogue planet is relatively young compared to the Earth, and some spectroscopic measurements suggest this planet's temperature is about 430° Celsius -- a bit too warm for our tastes (but maybe not for aliens?). [url]
• Within our own solar system, NASA's Cassini spacecraft has detected spurts of water from Saturn's moon Enceladus. This evidence leads to some speculation of a habitable zone on some icy moons where microbes might be able to survive. [url]

The Hubble is looking at a green gas cloud called Hanny’s Voorwerp. The object was discovered in 2007 by Dutch schoolteacher, Hanny van Arkel. [url]

The Kepler telescope found a solid planet about 40% bigger than Earth. That planet is more than a bit too hot for our biology, but there are at least a few hundred more planets in Kepler's sights. [url]

Mars might have giant caves! Or at least, it has big dark craters of some kind. [url]

Here's a "mysteries of space" timeline. Seriously not drawn to scale... especially a googol years in the future. [url]

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Science in Washington, D.C., says he can't comment on the Swiss work because he wasn't at the meeting and the data are unpublished.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."