The closest we've come so far to identifying Earth-like planets around other stars is in the identification of so-called 'super Earths.' Calculations designed to model the composition of such planets say that worlds up to about ten Earth masses are rocky rather than gaseous. Some of these, as we have in the case of Gliese 581, have even excited interest in their possible habitability. We'd like to find ways beyond the now conventional radial velocity and transit studies to identify more such worlds. Now a new planet may have been found around GJ 436, a red dwarf already known to host a Neptune-mass planet in a tight 2.6 day orbit. This is interesting work because of the methods used. Ignasi Ribas (Institut de Ciències de l'Espai, Spain) and team have taken a close look at the known planet and are arguing it is possible to identify a second world, a super-Earth, through the telltale variations in the transit duration of GJ 436b, the already known 'hot Neptune.' Giving the game away is...

Planets around other stars are too faint to be imaged directly, and although claims have been made for such detections (2M1207b is a case in point), it's safe to say that our current techniques need significant upgrading to achieve reliable images of such distant worlds. But studying terrestrial planets is a long-term objective and numerous studies have gone into concepts like Terrestrial Planet Finder and Darwin. One day and with some instrument we will indeed be looking at an exoplanet as small as the Earth, working with estimates of surface temperatures and checking its atmosphere for biomarkers that flag the presence of life. So let's suppose that in fifteen years or so we're looking at actual reflected light from a terrestrial world. What else can we learn about the place? The brightness of a planet like this can be affected by many things, including the presence of deserts on the surface or bright clouds above it. An active weather pattern would indicate the presence of a...

I'm late getting to this one, because I wanted to get Mike Gruntman's paper on interstellar instrumentation finished. But for exoplanet enthusiasts like myself, the best news to come out of the recent American Astronomical Society meeting may have been the announcement of a new planet around the star HD 74156. So let's talk about it, an interesting find because we haven't had a new planet turn up just where predicted since Urbain Le Verrier and John C. Adams (independently) worked out the existence of Neptune by noting its effects on the motion of Uranus. Thus were calculations turned into observations and thence discovery. Rory Barnes (University of Arizona) has been working on a theory that led to the HD 74156 discovery for some time. His computer simulations (begun with Thomas Quinn while both were at the University of Washington) on the stability of extrasolar planetary systems showed a key fact: All systems whose planets were close enough to affect each other gravitationally...