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Tuesday, March 8, 2016

What Are the Odds a Meteorite Could Kill You?

Written by Brian Clark Howard

Rumors of a space rock accident in India raise the question of how common this is.

As scientists investigate a reported death from a meteorite strike in southern India over the weekend, we wondered about the probability of such a fatal accident. Most people have the sense that meteorite strikes on people are exceedingly rare, but how rare? (As of Wednesday morning, NASA has cast serious doubt on the reports from India, saying the more likely culprit was a land-based explosion.)

Regardless of the final story in India, a meteorite is a piece of rock that strikes the Earth from outer space. The most famous case in the U.S. happened in 1954, when Ann Hodges was hit by a space rock in Sylacauga, Alabama.

The softball-sized hunk of black rock crashed through her ceiling while she was napping on her couch, hitting her in the side. Hodges later fought with her landlord over ownership of the rock and suffered a nervous breakdown.

In October 1992, a meteorite that caused a bright fireball across the sky hit a woman's parked car in Peekskill, New York. In 1825, people reported that a man was killed and a woman was injured by a meteorite in Oriang, India, although scholars have not been able to confirm the incident.

In 1827, a man was said to be injured after being struck in the arm by a space rock in Mhow, India. Other reports list cattle or horses killed by meteorites. A meteorite disrupted a wedding party in 1929 and a funeral in 1924. Perhaps even more strangely, in 2007, Peruvian villagers were sickened after a meteorite impact released toxic arsenic fumes from the ground.

A large meteorite exploded above central Russia in 2013 with a force 20 to 30 times the Hiroshima bomb injured 1,200 people, mostly from broken glass, and caused $33 million in damage.

Still, injuries from space rock incidents remain extremely rare.

"You have a better chance of getting hit by a tornado and a bolt of lightning and a hurricane all at the same time," Michael Reynolds, a Florida State College astronomer and author of the book Falling Stars: A Guide to Meteors & Meteorites, previously told National Geographic.

Doing the Math: Meteorite Strikes

Putting a probability number on the chances of being hit by a space rock is difficult, since the events are so rare. Still, Tulane University earth sciences professor Stephen A. Nelson published a paper in 2014 that made the effort. He put the lifetime odds of dying from a local meteorite, asteroid, or comet impact at 1 in 1,600,000.

Compared with 1 in 90 for a car accident, 1 in 250 for a fire, 1 in 60,000 for a tornado, 1 in 135,000 for lightning, 1 in 8 million for a shark attack, or 1 in 195 million for winning the PowerBall lottery.

Nelson put the risk of dying from a large, global asteroid or comet impact at 1 in 75,000. If that seems surprisingly high, it's because when massive objects have hit the Earth in the geologic past, they have wiped out millions of organisms, even whole species. Most of the creatures aren't killed from the direct impact, but from the aftereffects, which include heat, radiation, and dust that clouds out the sun.

Astronomer Alan Harris made a similar calculation, finding that a human being has a 1 in 700,000 chance of getting killed by an impact from space in their lifetime, with most of the risk coming from a large-scale event.

It's unclear what evidence will emerge from this week's incident in India, but if it does prove to have been a meteorite, it will be remembered as a highly unusual accident.

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