On rare occasions, bright stars seem to appear in the night sky, remaining visible for days or weeks before fading from view. Sometimes the light of such a star becomes brighter than that of nearly any other celestial object before it vanishes as mysteriously as it appeared. Ancient observers were at a loss to explain these stars, and ascribed great importance to them as divine omens, keeping careful records of their sightings. Chinese observers, for example, recorded the appearance of one in Taurus in 1054.

Astronomer Tycho Brahe, credited with bestowing the name nova ("new star") on the phenomena, saw one in 1572, as did Johannes Kepler in 1604.

With the invention of the telescope (just a few years after Kepler's sighting) and the advent of star charts recording the positions of known stars, astronomers realized that novae were not "new stars," but were actually stars which...