• 25 tons of dust and sand-size particles burns up entering the atmosphere.
About once a year...
• A car-size asteroid hits Earth's atmosphere but typically burns up before reaching the surface.
Every thousand years or so...
• An object the size of a football field hits Earth and causes significant damage to the impact area.
Every few million years...
• If an object larger than 0.6 miles across struck Earth, it could cause mass extinction and threaten civilization.
Some Past Impacts
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An 80-foot-diameter asteroid hit what is now Arizona 20,000 to 50,000 years ago to form a crater three-quarters of a mile wide. It was the first crater identified as being caused by an asteroid impact.
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A massive object struck what is now northern Canada about 210 million years ago to create a 60-mile-wide impact crater. The impact probably created a massive fireball and ejected material that reached around the world.
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An enormous asteroid or comet struck what is now the Yucatan Peninsula in Mexico more than 65 million years ago. The event has been linked to an extinction of more than half of Earth's species. The 112- to-186-mile-wide crater is buried under thousands of feet of limestone.
SOURCE: NASA Jet Propulsion Laboratory | THE WASHINGTON POST