The European Southern Observatory has unveiled a new planet-hunter: TRAPPIST: TRAnsiting Planets and PlanetesImals Small Telescope. I know, I know, but we're running out of acronyms here, folks. If it makes you feel better, it was named after a beer. It sits in the high and dry Atacama desert in Chile, rapidly and autonomously scanning the sky, looking at millions of stars and recording their brightnesses. It does this over and again, looking for the tell-tale dip in starlight caused when a planet passes in front of its parent star. In the meantime, it also takes incredible pictures of the sky:
That's the Tarantula Nebula, a sprawling complex of gas and dust churning out stars at an incredible rate. To give you an idea of how luminous it is, at 180,000 light years away (that's 1.8 quintillion kilometers, or more than a quintillion miles!) it's still visible to the naked eye (if you live in the southern hemisphere, that is). TRAPPIST's primary mission is to look for transiting planets as well as comets visible in the southern skies, but like any good telescope pointing up it's capable of all sorts of good science -- if, for example, there are any changes in the Tarantula (a star explodes, or flares up) TRAPPIST will catch it.
This is all pretty amazing considering the telescope is only 60 cm (20 inches) in diameter! Because the transit method looks for dips in a star's brightness, it's best to look at bright stars; they give off so much light that even a small dip is easier to see. You don't need a honking big 'scope to look at bright stars, and in fact something smaller is even better: it can see larger areas of sky at once, and won't overexpose the detector like a bigger 'scope might do when it floods the camera with starlight. Small telescopes are less expensive and easier to design, too; TRAPPIST went from being just an idea to getting its first images in only two years. And it's fully robotic! It does its thing on its own, preprogrammed to sweep the heavens and send the data to astronomers without them ever having to actually be at the dome. Other such smaller-scale projects are popping up all over the planet, and I think that's terrific. You don't always need a huge expensive piece of equipment to do solid science, and, amazingly, even a telescope no bigger than one you can keep in your garage can actually be used to discover planets orbiting other stars!