Hi! I've a blog post up reacting to and summarizing http://abitmoredetail.wordpress.com/2012/04/10/brief-note-on-earth-like-... an interesting new paper hosted at arXiv, http://arxiv.org/abs/1203.5104 "Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating", by Barnes, Mullins, et al. The paper makes the argument that classical calculation of a star's habitable zone, based on the radiant energy produced by a star, don't take into consideration the energy produced by a star's tidal forces. For worlds orbiting stars closely, especially dim red dwarf stars which produce so little radiant energy that any world with a potentially Earth-like climate would experience significant tides from their primary, this could have a very significant impact. The authors predict that many of these worlds would be more geologically active than even Io, receiving so much energy via stellar tides that they'd become "Tidal Venuses", losing their water to space via evaporation in hundreds of millions of years. This is particularly risks for planets orbiting very low-mass red dwarfs (less than 20% the mass of the sun, compare Barnard's Star or Ross 128) or planets with very eccentric orbits. The paper takes a look at Gliese 667Cc and judges that the planet is not likely to be such. Other exoplanets, however ... Is this what happened to Arcadia?