"Some astronomers believe a hidden mini star nicknamed Nemesis is orbiting the sun, but a new analysis of life extinction cycles on Earth suggests this dark companion may not exist." The Christian Science Monitor updates a old theory about life cycles on planet Earth: "Nemesis was first proposed in 1984 to explain perplexing cycles in mass extinctions on Earth. About every 27 million years, almost like clockwork, there is a significantly higher likelihood that a mass extinction will take place on our planet – akin to the apocalypse that killed off the dinosaurs (and much of the rest of Earth's life) about 65.5 million years ago."