© Science Photo Library;
About 66 million years ago, an asteroid slammed into Earth, wiping out more than A 75 per cent of all life on our planet – including the dinosaurs. What caused that asteroid to come our way has perplexed scientists for a long time. Was it just a coincidence, or were bigger powers at play? Back in 1984, a group of astronomers suggested the latter with a pretty controversial paper: Marc Davis, Piet Hut and Richard Muller proposed that every 26 to 30 million years, a companion star to our Sun would swing past the Solar System, potentially disrupting a family of asteroids and comets at our Solar System’s edge – those in the Kuiper Belt and Oort Cloud – and sending some our way. They dubbed this star Nemesis, after the Greek goddess of retribution.
The idea was based on the discovery that Earth had experienced not just one, but multiple extinctions in its past. These seem to have occurred roughly every 26 to 30 million years, based on the number of large craters that have been found and aged. A number of theories were proposed for why this might be, from regular volcanic activity to a hidden giant planet in the Solar System.