Who says bigger is better?
A trio of small, 10cm (4 in) telescopes have discovered a new extrasolar planet (i.e., one not in our solar system). These guys weren’t amateurs, though - they are members of TrES (Trans-Atlantic Exoplanet Survey), a wordwide group.
How do you detect a planet? Remember, it’s hundreds or thousands of light years away, and so dim that you couldn’t possibly see it directly beside its sun. The trick they use is to look for transits of the planet across the face of its sun - remember the recent Transit of Venus? Venus passed between us and the Sun (our Sun!), which we say as a dark spot on the sun, moving slowly across. If an extrasolar planet passes in front of a far away star, the effect is the same - some of the light from that star is blocked, and it will appear dimmer while the transit is occurring. Of course, we can’t see the actual crossing - the star is too far away for us to resolve it as a disk, so we can only see a point. But the periodic dimming of the star as the planet goes around is detectable, and that’s what they’ve done with these relatively cheap telescopes. Pretty neat, hey? This can only be seen on very bright stars, which is why small telescopes can get involved. It also means we can only detect large planets (Jupiter size) because they’re the only ones that give a big enough dip in brightness to be detected.