hot, young stars. Some of these stars are clustered near the point of the triangularly shaped “island.” Indeed, nebulae like Carinae act as nurseries for young stars. 
    Eta Carinae, one of the most prominent denizens of the Keyhole Nebula, is a peculiar star. Its brightness has varied dramatically, and unusually, over the last several hundred years. The star was originally named “eta,” the seventh letter in the Greek alphabet, because when it was catalogued, by Johann Beyer in the early seventeenth century, it was the seventh brightest star in the constellation. Now, however, it is invisible to the naked eye, and there are more than seven stars in the constellation that are brighter. Yet Eta Carinae was once 100 times brighter than it is