Re:Real ingenuity (Score 5, Informative)

I don't mean to diminish the cleverness of those involved in this project at all, but the article summary is a little misleading. While the discovery was made with very small-scale telescopes, the confirmation that this was actually a planet came from two large telescopes, the Harlan J. Smith Telescope (2.7 meter aperture) and the Hobby-Eberly Telescope (9.2 meter effective aperture), as the linked article mentions.

Finding extrasolar planets by the transit method, where you moniter large fields of stars and look for brightness variations as a planet passes in front of one of your targets and blocks some light, is pretty straight-forward. You tend to only need somewhere between 0.1% and 1% precision in your photometry, which requires some work to achieve, but is by no means prohibitive. So it's a good technique for amateurs to get involved with, especially when you consider that smaller telescopes tend to have larger fields of view, so you can moniter more stars at once. But the main stumbling block transit-searchers have run into is the false positive rate. The biggest surveys have found a huge false-positive rate (90-95%) among the planet candidates. It turns out there are lots of things that can make a star dim at fixed intervals, from grazing binaries to starspots.

As a result, transit planet candidates are only considered confirmed when there are measurements of a radial-velocity wobble consistent with the orbital period found by the transit. To get the radial velocity precision you need (for the Hot Jupiters transits detect, precision of tens of meters per second is sufficient), it takes a precise, high resolution spectrograph (very expensive), mounted on a large telescope (at least a couple meters).

I should also point out that transit searches are sensitive mainly to close-in planets. The sensitivity function drops very quickly as the planet moves further out (both because you need a longer sustained campaign, and because the chances of the planet's orbit crossing the star decreases). All the transit detections thus far have been from planets with several-day orbits. While this is interesting science, there's a lot of work to be done with planets in other regimes. The straight-up radial velocity technique gets you planets at seperations between 0 and 5 AU or so (over 150 planets found this way so far), the microlensing method can also detect planets at much larger orbital separations (2 or 3 planets up until now), and direct imaging is ideally suited for large-seperation planets (only the 1 good planet at this point). My point is that you can't cover this whole range of parameter space with small telescopes alone. Radial velocity and direct imaging require large investments in hardware, both in the large telescope itself and the instrumentation (disclaimer: I work on direct imaging, that's why I keep bringing it up). It's also important to note that one of the reasons people find transiting planets so interesting is the possibility of getting spectral information out of the planets. NASA's Spitzer space telescope recently detected the secondary eclipse (the loss of light when the planet is hidden behind the star) of two transiting extrasolar planets. This is pretty exciting science, since you can really compare data to models this way, but it requires some extensive telescope set-ups to get it done.

So again, this is certainly a great project for getting amateurs involved in the planet-finding game, and I"m very impressed with this result. But don't close down Keck and the VLT and Hubble just yet; there's a lot of work to be done in extrasolar planet research, and much of it requires large telescopes with new (read: expensive) instruments.