Crux was visible to the ancient Greeks as the southernmost part of Centaurus, but over the millennia precession moved it too far south to be visible from European latitudes (it is currently visible just north of the tropics and everywhere south of that), and its existence was forgotten. It was rediscovered in the late 16th or 17th century, though exactly when and by whom is a matter of debate. Petrus Plancius mapped a cross in the late 1500's (though in the wrong position), and Bayer's atlas of 1603 showed a cross superimposed on the Centaur's rear legs, with an equally incorrect position (based on Ptolemy's less than stellar measurements). After Edmund Halley made the first accurate measurements of its stars in 1676 things settled down, and the final division of Crux from Centaurus is generally credited to Augustin Royer (in 1679). |
