In 2002, the brightness of the star shot up suddenly. It was thought to be a simple nova, which is what happens when the remaining core of a dead star (known as a white dwarf) accumulates too much hydrogen gas from a neighboring star, causing a fantastic explosion. The star dimmed after a couple weeks, as expected, and scientists put it in the record books as a nova.
But less than a month later, the star burst into light again. Since the time period between the explosions was too short to be caused as two separate novas, astronomers were puzzled and took a closer look.
