Astronomers spotted the brightest supernova seen in modern times almost 17 years ago, and the Hubble Space Telescope has been keeping tabs on it since its launch. Just last year Supernova 1987A put on a new show when a shockwave from its explosion smashed into a ring of gas that had probably been shed 20,000 years ago. Under the pressure from the shockwave, the gas has started to glow, like a ring of pearls around the centre of the explosion. More hotspots will keep appearing until the entire ring of gas is ablaze as it absorbs the full force of the shockwave.