Dinosaur-killing asteroid did not trigger a long 'nuclear winter' after all

The asteroid that wiped out the dinosaurs did not trigger a long-lasting impact winter, scientists have found — a discovery that raises new questions about what happened on Earth just after it hit. 
One spring day 66 million years ago, a 6-mile-wide (10 kilometers) asteroid smashed into the Yucatán Peninsula and upended life on Earth. This event, called the Chicxulub impact, triggered a mass extinction that wiped out 75% of species, including all non-avian dinosaurs. 
But how exactly it killed the dinosaurs is a bit of a mystery — after all, they weren't congregated beneath the asteroid, waiting to be squashed. For decades, scientists speculated that the impact tossed so much dust and dirt into the atmosphere that it triggered an "impact winter" (similar to a nuclear winter) — a period of prolonged cooling during which global temperatures plummeted. 
However, a study published March 22 in the journal Geology tells a different story.
Dinosaur-killing asteroid did not trigger a long 'nuclear winter' after all