You can organize a constellation’s stars in many ways — by brightness, color, position, and so on. But the system that astronomers have been using for centuries can’t quite make up its mind. In most cases, it goes by brightness. In others, it goes by position. And in some, there doesn’t seem to be a guiding principle at all. An example of the latter is Corvus, the crow. It’s due south at nightfall, to the lower right of bright Spica, the leading light of Virgo. Four stars form an angled box that looks like a sail. A fainter star is off the lower right point of the sail. Yet it receives top billing. The naming system was devised more than four centuries ago by German astronomer Johann Bayer. He labeled the bright stars in each constellation with the letters of the Greek alphabet. “Alpha” usually designated the brightest star. In some instances, though, the title went to a star that was the starting point for an easily defined pattern. In the case of Corvus, though, there doesn’t seem to
