A new theory: freezing darkness killed the dinosaurs

When a giant asteroid careened into Earth about 66 million years ago, the enormous collision led to the formation of an airborne “curtain” of sulfate molecules that blocked the sun’s light and led to years of freezing cold and darkness, a new study finds.The finding shows how these droplets, or aerosols, of sulfuric acid formed high in the atmosphere, and likely contributed to the deaths of 75 percent of all animals on Earth, including nonavian dinosaurs such as Tyrannosaurus r