Scientists Say Second Killer Asteroid May Have Struck Earth
2022-08-29
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1Scientists are investigating the possibility that a second asteroid hit Earth about the same time as the one believed to have killed off nearly all dinosaur life.
2The investigation is linked to a smaller crater recently discovered in the ocean.
3Researchers say the crater may have been created by a large asteroid.
4Scientists have long believed that a large asteroid hit Earth about 66 million years ago near Mexico's Yucatán Peninsula.
5They estimate the force of the crash to be equal to the strength of about 10 billion nuclear bombs.
6The strike, or impact, is believed to have caused widespread wildfires, earthquakes and huge ocean waves, or tsunamis.
7Scientists also believe the event caused a release of chemicals into the atmosphere that led to severe cooling.
8The climate-changing event is blamed for causing the disappearance of more than 70 percent of plant and animal life.
9All dinosaurs that were not bird-like died out.
10That strike created a huge crater about 180 kilometers wide and 900 meters deep.
11Researchers say the newly discovered crater, found in the North Atlantic Ocean, is much smaller.
12It is about 8.5 kilometers wide. It is buried up to 400 meters below the seabed off the coast of Guinea, in West Africa.
13Scientists found the crater by using seismic instruments.
14Such tools are designed to measure earthquakes and pick up other vibration signals on Earth.
15The crater was discovered by Uisdean Nicholson, a geologist at Heriot-Watt University in Edinburgh, Scotland.
16At the time, Nicholson was working on an ocean-mapping project involving seabed spreading.
17This kind of spreading is what caused the African and American continents to separate over time, leading to formation of the Atlantic Ocean.
18"I've interpreted lots of seismic data in my time, but had never seen anything like this," Nicholson said in a statement.
19He added that he was surprised to see that the data described a huge crater "with very unusual characteristics."
20Nicholson said the crater has several elements that suggest it could have been created by an asteroid.
21But he noted that researchers will need to investigate more before that theory can be confirmed.
22A team plans to visit the crater to drill into the seabed and collect mineral samples.
23The team's findings were recently reported in a study in the publication Science Advances.
24Veronica Bray is another member of the research team. She is a planetary scientist at the University of Arizona.
25Bray used computer simulations to predict the effects that such an impact would have had.
26The simulations suggested the crater was created by a 400-meter asteroid crashing into 500 to 800 meters of water.
27She said this would have likely caused a 900-meter-high tsunami, as well as an earthquake with a strength of 6.5.
28Bray noted the effects of the newly discovered crater would have been much less than the one that hit present day Mexico.
29But it still would have added "significantly" to local destruction.
30She said the new discovery makes her wonder whether there are other impact craters that scientists have not yet found.
31Nicholson said his team has considered the possibility that both impact craters could be linked.
32The researchers said they believe the newly discovered crater could have formed by the breakup of a parent asteroid.
33Sean Gulick is a crater impact expert at the University of Texas at Austin.
34He called the find an "exciting" discovery that could lead to further investigations of other possible impacts around the same time period.
35"Despite four billion years of impactors hitting Earth, only 200 have been discovered," Gulick said in a statement.
36"It is thus exciting news whenever a new potential impact is discovered, especially in the hard-to-explore (ocean) environment," he added.
37I'm Bryan Lynn.
1Scientists are investigating the possibility that a second asteroid hit Earth about the same time as the one believed to have killed off nearly all dinosaur life. 2The investigation is linked to a smaller crater recently discovered in the ocean. Researchers say the crater may have been created by a large asteroid. 3Scientists have long believed that a large asteroid hit Earth about 66 million years ago near Mexico's Yucatán Peninsula. They estimate the force of the crash to be equal to the strength of about 10 billion nuclear bombs. 4The strike, or impact, is believed to have caused widespread wildfires, earthquakes and huge ocean waves, or tsunamis. Scientists also believe the event caused a release of chemicals into the atmosphere that led to severe cooling. 5The climate-changing event is blamed for causing the disappearance of more than 70 percent of plant and animal life. All dinosaurs that were not bird-like died out. 6That strike created a huge crater about 180 kilometers wide and 900 meters deep. 7Researchers say the newly discovered crater, found in the North Atlantic Ocean, is much smaller. It is about 8.5 kilometers wide. It is buried up to 400 meters below the seabed off the coast of Guinea, in West Africa. 8Scientists found the crater by using seismic instruments. Such tools are designed to measure earthquakes and pick up other vibration signals on Earth. 9The crater was discovered by Uisdean Nicholson, a geologist at Heriot-Watt University in Edinburgh, Scotland. At the time, Nicholson was working on an ocean-mapping project involving seabed spreading. This kind of spreading is what caused the African and American continents to separate over time, leading to formation of the Atlantic Ocean. 10"I've interpreted lots of seismic data in my time, but had never seen anything like this," Nicholson said in a statement. He added that he was surprised to see that the data described a huge crater "with very unusual characteristics." 11Nicholson said the crater has several elements that suggest it could have been created by an asteroid. But he noted that researchers will need to investigate more before that theory can be confirmed. A team plans to visit the crater to drill into the seabed and collect mineral samples. 12The team's findings were recently reported in a study in the publication Science Advances. 13Veronica Bray is another member of the research team. She is a planetary scientist at the University of Arizona. Bray used computer simulations to predict the effects that such an impact would have had. 14The simulations suggested the crater was created by a 400-meter asteroid crashing into 500 to 800 meters of water. She said this would have likely caused a 900-meter-high tsunami, as well as an earthquake with a strength of 6.5. 15Bray noted the effects of the newly discovered crater would have been much less than the one that hit present day Mexico. But it still would have added "significantly" to local destruction. She said the new discovery makes her wonder whether there are other impact craters that scientists have not yet found. 16Nicholson said his team has considered the possibility that both impact craters could be linked. The researchers said they believe the newly discovered crater could have formed by the breakup of a parent asteroid. 17Sean Gulick is a crater impact expert at the University of Texas at Austin. He called the find an "exciting" discovery that could lead to further investigations of other possible impacts around the same time period. 18"Despite four billion years of impactors hitting Earth, only 200 have been discovered," Gulick said in a statement. "It is thus exciting news whenever a new potential impact is discovered, especially in the hard-to-explore (ocean) environment," he added. 19I'm Bryan Lynn. 20Bryan Lynn wrote this story for VOA Learning English, based on reports from Heriot-Watt University, the University of Arizona and Science Advances. 21________________________________________________________ 22Words in This Story 23asteroid - n. a rocky object that goes around the sun like a planet 24vibration - n. a shaking movement 25interpret - v. to explain of explore the meaning of something 26characteristic - n. a typical or noticeable quality that makes one person or thing different from others 27sample - n. a small amount of something that gives you information about the thing it was taken from 28simulation - n. a creation of something that behaves or looks like something real but is not 29significant - adj. important or notable 30What do you think of this story? We want to hear from you. We have a new comment system. Here is how it works: 31Each time you return to comment on the Learning English site, you can use your account and see your comments and replies to them. Our comment policy is here.