Supernovae are usually the death of stars but for at least one, explosion didn't mark the end, scientists report today in Nature.

What they saw: Supernova iPTF14hls was first observed in 2014. Unlike other supernovae that typically shine for about 100 days before fading, this one — about 500 million light-years away — grew brighter and then dimmer five times over 600 days. Even more peculiar, archives showed another explosion was observed in the same location in 1954.

Why its happening: Unclear. According to one theory, repeated explosions can occur in stars 95 -130 times more massive than the Sun. They, too, would end in a supernova and ultimately collapse into a black hole.

Yes, but: The supernova's constant temperature doesn't fit with the theory and it released more energy than theory predicts.

What's next: Supernova iPTF14hls may finally be fading, reports Lisa Grossman in Science News. "I am not making any more predictions about this thing," study author Iair Arcavi told Grossman. "It surprised us every time."