Two teams of astronomers made headlines in November after announcing they had photographed planets orbiting regular stars other than our own sun. (Such bodies are known as extrasolar planets, or exoplanets.) One of those planets, Fomalhaut b, the companion to a star called Fomalhaut some 25 light-years away, was spotted by the Hubble Space Telescope; a star known as HR 8799, nearly 130 light-years distant, was found by ground-based observations to harbor a system of at least three planets...