What Happened to Earth? It's believed that an asteroid or a comet struck the Earth some 65 million years ago causing massive damage and wiping out the dinosaurs. But scientists say that wasn't the first time that such thing happened to our planet. Based on new evidence, they believe a similar event occured 185 million years earlier and did even worse damage. Whatever crashed into the earth then would have been 6 to 12 kilometers across. The impact awakened volcanoes and set up huge plumes of ash and dust that made the planet cold and dark for centuries. (end)