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April 13, 2019

Ten years from today, the asteroid Apophis will pass just 20,000 miles from Earth — close enough to look like a faint star streaking across the night sky.

When Apophis was discovered, though, it looked like the light show might be much more ominous. Astronomers initially gave Apophis a 2.7 percent chance of hitting Earth in 2029. Since the asteroid is about a quarter of a mile wide, an impact would devastate thousands of square miles.

That scary thought inspired a scary name. Apophis is the Greek name for Apep, the Egyptian god of chaos. He was depicted as a snake-like creature who lived in the dark underworld. Each night, as the Sun passed through that realm, Apep tried to eat the Sun god, Re, and plunge the world into darkness and chaos.

As astronomers got a better track of Apophis’s orbit, though, they ruled out a collision in 2029. But there was still a possibility that it could hit us in 2036. It would require Apophis to fly through a point in space only a few hundred yards wide during the 2029 encounter. More tracking has ruled out that possibility as well. But we’re still not completely safe. There’s a one-in-150,000 chance it’ll hit us in 2068.

Earth will have a big effect on Apophis during the 2029 encounter. It’ll dramatically change its orbit, moving its average distance from the Sun outward by more than 15 million miles.

Script by Damond Benningfield

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