“Someone Always Wins the Lottery, but it Probably Won’t be You”
What are the chances of being hit by an asteroid? What is the likelihood of any solid object plunging from outer space and landing on our heads?
The Wall Street Journal and other news outlets informed us a man in the southern India state of Tamil Nadu suffered fatal injuries February 6 when a meteorite smashed to the ground with explosive force, leaving a four-foot deep crater at the campus of Bharathidasan Engineering College. Authorities in India reported the man died after being struck by flying debris, and three others were injured. The U.S. National Aeronautics and Space Administration (NASA) said there was no record in modern times of anyone being killed by a meteorite. Four days later, experts doubted the hole in the ground and the death and injuries had been caused by a meteorite.
What was it? A meteoroid is a small particle from an asteroid or a comet that travels around the sun. When a meteoroid enters the earth’s atmosphere, it burns up and is often seen as the light phenomena we know as a shooting star. A meteorite is a meteoroid that survived entry into the atmosphere and falls to the earth. And that’s not all that’s up there.
Derek Sears, a NASA meteorite and asteroid expert, suggested the thing that hit the Indian college might have been an object falling from an aircraft passing overhead. According to Discovery.com. other experts think it might have been a bit of space junk that entered the earth’s atmosphere without completely burning. The U.S. National Research Council estimates that 5,400 tons of man-made rubbish in space have landed back on earth in the last 40 years and there haven’t been report of injuries.
The NRC’s report Defending Planet Earth: Near Object Surveys and Hazard Mitigation Strategies says about 100 tons of very small objects, mostly in the form of dust, fall to earth every day. A meteor about 30 meters across smashed in sparsely populated Siberia in 1908, flattening a forest. The NRC estimates a one in 200 chance per year of an impact of that magnitude hitting somewhere on earth. In 2013, meteor fragments exploded over Russia’s Ural Mountains, damaging thousands of buildings and injuring hundreds of people. Russian scientists said the meteor was several yards in diameter and weighed about 10 metric tons. Scientists believe a very large asteroid landed on earth and wiped out dinosaurs about 66 million years ago.
NASA’s Near Earth Objects program is tracking more than 837 objects that are more than one kilometer across. (One Kilometer is equal to 0.6214 miles.) A collision between earth and an object with a diameter of more than 3 kilometers (1.86 miles) would be considered catastrophic, scientists say, and that is expected to happen every few million years.
Scientists say the odds of any individuals being hit are really very low. NASA figures an individual would be a target of about one square meter in area, and the earth has a surface area of about 400,000,0000 square kilometers. Assuming objects can land anywhere, there would mean a chance of one in 20,000,000,000,000 (that’s 20 trillion) of any particular square meter being hit.
Of course, there’s more than one way to figure odds. Science blogger and author Phil Plait, writing in Discover Magazine, notes we’re more likely to get killed by a meteorite than hit by one, because damage from explosive debris is more likely than direct impact from outer space. He also explains astronomer Alan Harris has calculated that a person’s lifetime odds of being killed by asteroid impact are about one in 700,000.
“We’re lousy at understanding low probability events,” Plait writes. “One in 700,000 is a ridiculously low probability but it’s hard to grasp. As a comparison you’re more likely to die in a fireworks accident. …that’s a slightly higher chance than being killed by a terrorist. Despite propaganda to the contrary, the odds of any given person being killed by a terrorist attack are incredibly low. While terrorists attacks in the long run are a near certainty, the odds of you getting killed are very low. It’s like the lottery. Someone wins every time, eventually, but chances are it won’t be you.” .