Scientists have learned that the brightest supernova ever observed wasn't an exploding star at all. Instead, the star was ripped apart by a giant black hole. How big of a black hole? Up to 3 billion times more massive than the sun. Scientists say the hole's gravitational pull "spaghettified" the star, stretching it until it was pulled apart. That's called a tidal disruption. When scientists first discovered the event, they said it was twice as bright as any supernova ever seen. But after months of further study, they found clues that it likely wasn't a supernova. First was the red backdrop. Large, reddish galaxies usually aren't where you find the kind of stars needed for the brightest supernovas. Another clue: It happened at the center of the galaxy, where super-massive black holes usually reside. The final tip was heat. Instead of cooling down over time like a supernova normally would, the area got hot again and stayed warm for months. Even if it wasn't the most brilliant supernova ever, the event is still rare. Scientists have discovered a tidal disruption only about 10 times.