Supernovas are hard to detect. Scientists just found a way to spot them hours after they explode

The early stages of a supernova explosion are revelatory in what they can reveal about stars that go boom. But while catching them immediately after they detonate has proven largely elusive, astronomers now think they have developed a foolproof way to spot a young supernova.

Although we know what type of star will go supernova, we cannot predict when a star in a distant galaxy might explode. In the past it has been down to pure luck as to whether we were looking in the right direction at the right time to see a supernova just hours after it blows up.

Large-scale surveys that scan the entire night sky every few days have evened the odds somewhat, but now the challenge faced by astronomers is spotting a young supernova among the huge amounts of data that these surveys collect. To surmount