Detecting an Exoplanet... Without a Telescope

Years ago, when the first transiting exoplanet (HD 209458b) was found, I was startled to realize that it could be easily detected using a small, inexpensive telescope. Transiting exoplanets are planets that orbit other stars, and from Earth we just so happen to see their orbit edge-on. That means it passes in front of their parent star (that's the transit bit), blocking a fraction of its light. A tiny fraction, usually far less than 1%. But if the star is bright this dip in brightness can be spo...