![]() A 2015 study estimated that the crater may have been created by a comet about 9.3 miles (15 km) wide.įrom 2013 to 2014, the scientists in the new study collected samples from the 0.93-mile-thick (1.5 km) layer of rock that filled the Sudbury crater. It's also the second-largest and best-preserved crater on Earth, measuring about 93 to 161 miles (150 to 260 km) in diameter. "These are actually chucks of the moon and Mars that have been blown off those planets by impacts and then spent a long time in space before finally hitting Earth as a meteorite.To see what effects giant impacts might have had on the surface of the Earth, the researchers analyzed one of the oldest meteor craters on the planet, the 1.85-billion-year-old Sudbury basin in Canada. "We actually get a few meteorites from the moon and Mars," Moorhead said. In other words, the meteor will not burn up completely, and some remnant meteorites will fall to the ground. For example, " if the is a chunk of an asteroid, instead of a chunk of a comet, it's likely to be a little denser, a little stronger and more likely to produce a meteorite."Īlso, if the meteor is approaching Earth at a slower speed, the rock will likely survive its collision with Earth's atmosphere, Moorhead added. "Only those meteoroids that happen to be made of stronger material produce meteorites," she said. This is because most meteorites are believed to come from comets, which are more fragile than asteroids. However, even large meteorite events that originate from asteroids, which can be tracked in space, are unpredictable.įortunately, between 90 and 95 percent of meteors don't survive the fall through the Earth's atmosphere to produce meteorites, Moorhead explained. Generally, astronomers are unable to predict meteorite impacts, largely because meteoroids traveling in outer space are too small to detect. Because of its remote location, the event is an example of a meteorite that would have gone undetected had it not been so large, Cooke and Moorhead explained. The meteorite exploded over the Tunguska River on June 30, 1908, and flattened 500,000 acres (2,000 square km) of uninhabited forest. California-Davis)Īnother major collision was the Tunguska meteorite, which was larger than Chelyabinsk and 10 times more energetic. Several small stones were found in the area after the massive impact. This is a sample of a meteorite that was found following the Chelyabinsk event in Russia in 2013. "So, you don't have to watch for the falling rocks - you have to worry about the shockwave."įor example, the Chelyabinsk meteor - an asteroid the size of a six-story building that entered Earth's atmosphere in February 2013 over Russia - broke apart 15 miles (24 km) above the ground and generated a shock wave equivalent to a 500-kiloton explosion, Cooke said. "What causes the most damage is the shock wave produced by the meteor when it breaks apart in atmosphere," Cooke said. However, the pieces of rock falling from the sky are not even the greatest concern regarding meteor impacts, Cooke said. Thankfully, no one was injured during these events. In another incident, meteorites crashed into the back end of a Chevy Malibu in Peekskill, New York, in 1992, Cooke and Moorhead said. When the Grimsby meteorite landed in Ontario, Canada in 2009, for example, it broke the windshield of an SUV. (0.45 kilograms) meteorite traveling upward of 200 mph (322 km/h) can fall through the roof of a house or shatter a car windshield. While it may seem like these tiny pieces of rock wouldn't do much damage, a 1-lb. Most meteorites that are found on the ground weigh less than a pound. "They are not strong enough to survive passage through the atmosphere at 132,000 mph (212,433 km/h) and so never produce meteorites - they are totally vaporized by the time they make it to 50 miles (80 km) altitude." Unpredictable catastrophes " Perseids come from Comet Swift-Tuttle and are very fragile, being an ice-dust mix," Cooke said.
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