At least 2 mass #extinction events in Earth's history were likely caused by the devastating effects of nearby #supernova explosions. That's according to a new study released today by researchers at Keele University in England. The researchers said these super-powerful blasts - caused by the death of a massive star - may have previously stripped our planet's atmosphere of its ozone, sparked acid rain and exposed life to harmful ultraviolet radiation from the sun. They believe a supernova explosio