Dino-killing asteroid might have brought 2 years of darkness

A NASA-backed study has found tremendous amounts of soot lofted into air from global wildfires, following the dinosaur-killing asteroid strike 66 million years ago, would have plunged Earth into darkness for nearly two years. This would have shut down photosynthesis and drastically cooled the planet leading to mass extinction of three-fourths of species on Earth back then, the study added.