NASA’s Bold Plan to Save Earth From Killer Asteroids

Just beyond Earth’s home in the solar system, about 94 million miles from the Sun, a coal-black asteroid slowly rotates as it orbits our star. It’s about 1,650 feet across, with a slight bulge around the middle, like a spinning top. Its low density means it’s not solid, but instead it’s likely a crumbly pile of carbon-rich rocks held together by gravity.

The asteroid is called Bennu, and every six years, its egg-shaped orbital path brings it just 185,000 miles from Earth — roughly 53,000 miles closer than our moon. In about 200 years, there’s a 1-in-2,700 chance it could sail close enough for Earth’s gravity to reel it in. That would be very bad.

The impact would excavate a crater nearly three miles wide and 1,500 feet deep. Locations three miles away would be buried under 50 feet of rock raining down. It would trigger a 6.7-magnitude earthquake. But the real damage would come from the air burst, caused by the meteor hurtling through the atmosphere, which could collapse buildings and tear down trees up to 30 miles away.

Luckily for us, asteroids the size of Bennu, and giant asteroids like the one that helped kill the dinosaurs 65 million years ago, don’t cross Earth’s path often. But smaller ones do all the time. They enter our atmosphere as meteors, where many blow up in mid-air; some make their way to the ground or sea. The good news is that we’re getting better at finding them — but we’re still unprepared if one does make its way to Earth.

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