00:03We all know how the dinosaurs died. A giant asteroid traveling through space at thousands
00:08of miles an hour collided with our planet. But what happened next? What really killed the
00:13dinosaurs? After all, despite being 7.5 miles wide, the asteroid that killed them is still
00:18quite small on a planetary scale. Well, the real reason, experts say, is that the asteroid impact
00:23kicked up a ton of dust. Researchers look at sedimentary rock to determine what the world
00:27was like at different periods, finding that there's a dust layer which corresponds to
00:31the time when the asteroid hit Earth. Under that layer, which is found globally, we find
00:35dinosaurs. But above it, we don't. Meaning that dust which was kicked up into the sky
00:39likely darkened the sun, blocking the warmth and light plants needed to survive. The situation
00:44would have made its way all the way up the food chain pretty quickly, causing mass die-offs
00:48during a planetary winter. This could have also affected the very chemistry of the oceans,
00:53killing off many of the sea creatures there as well. Experts also believe the situation
00:57was exacerbated by severe volcanoes that erupted around the same time as the asteroid impact.
01:02So what if it happens again? Well, NASA scientists are working on that. But in the meantime, astronomers
01:07are rigorously tracking any and all that might come too close to our planet.
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