In 2009 a giant star 25 times more massive than the sun simply vanished. OK, it wasn’t quite that simple. It underwent a period of brightening, increasing in luminosity to a million suns, just as if it was ready to explode into a supernova. But then it faded rather than exploding. And when astronomers tried to see the star using the Large Binocular Telescope (LBT), Hubble and the Spitzer space telescope, they couldn’t see anything.