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Scientists Say Second Killer Asteroid May Have Struck Earth

时间:2022-10-05 22:59:14

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Scientists are investigating the possibility that a second asteroid1 hit Earth about the same time as the one believed to have killed off nearly all dinosaur2 life.

The investigation3 is linked to a smaller crater4 recently discovered in the ocean. Researchers say the crater may have been created by a large asteroid.

Scientists 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.

The strike, or impact, is believed to have caused widespread wildfires, earthquakes and huge ocean waves, or tsunamis6. Scientists also believe the event caused a release of chemicals into the atmosphere that led to severe cooling.

The climate-changing event is blamed for causing the disappearance7 of more than 70 percent of plant and animal life. All dinosaurs8 that were not bird-like died out.

That strike created a huge crater about 180 kilometers wide and 900 meters deep.

Researchers 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.

Scientists found the crater by using seismic9 instruments. Such tools are designed to measure earthquakes and pick up other vibration10 signals on Earth.

The crater was discovered by Uisdean Nicholson, a geologist11 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.

"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."

Nicholson said the crater has several elements that suggest it could have been created by an asteroid. But he noted12 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.

The team's findings were recently reported in a study in the publication Science Advances.

Veronica Bray13 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.

The 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 tsunami5, as well as an earthquake with a strength of 6.5.

Bray 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 craters14 that scientists have not yet found.

Nicholson 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.

Sean 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 investigations15 of other possible impacts around the same time period.

"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.

Words in This Story

asteroid – n. a rocky object that goes around the sun like a planet

vibration – n. a shaking movement

interpret – v. to explain of explore the meaning of something

characteristic – n. a typical or noticeable quality that makes one person or thing different from others

sample – n. a small amount of something that gives you information about the thing it was taken from

simulation – n. a creation of something that behaves or looks like something real but is not

significant – adj. important or notable


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1 asteroid uo1yD     
n.小行星;海盘车(动物)
参考例句:
  • Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
  • It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小,但这样的危险还是存在的。
2 dinosaur xuSxp     
n.恐龙
参考例句:
  • Are you trying to tell me that David was attacked by a dinosaur?你是想要告诉我大卫被一支恐龙所攻击?
  • He stared at the faithful miniature of the dinosaur.他凝视著精确的恐龙缩小模型。
3 investigation MRKzq     
n.调查,调查研究
参考例句:
  • In an investigation,a new fact became known, which told against him.在调查中新发现了一件对他不利的事实。
  • He drew the conclusion by building on his own investigation.他根据自己的调查研究作出结论。
4 crater WofzH     
n.火山口,弹坑
参考例句:
  • With a telescope you can see the huge crater of Ve-suvius.用望远镜你能看到巨大的维苏威火山口。
  • They came to the lip of a dead crater.他们来到了一个死火山口。
5 tsunami bpAyo     
n.海啸
参考例句:
  • Powerful quake sparks tsunami warning in Japan.大地震触发了日本的海啸预警。
  • Coastlines all around the Indian Ocean inundated by a huge tsunami.大海啸把印度洋沿岸地区都淹没了。
6 tsunamis a759fe8c9bbe15580d54b753ecec1e73     
n.海啸( tsunami的名词复数 )
参考例句:
  • Our oceans are alive with earthquakes, volcanoes, and more recently, tsunamis. 海中充满着地震、火山,包括最近发生的海啸。 来自常春藤生活英语杂志-2006年2月号
  • Please tell me something more about tsunamis! 请您给我讲讲海啸吧! 来自辞典例句
7 disappearance ouEx5     
n.消失,消散,失踪
参考例句:
  • He was hard put to it to explain her disappearance.他难以说明她为什么不见了。
  • Her disappearance gave rise to the wildest rumours.她失踪一事引起了各种流言蜚语。
8 dinosaurs 87f9c39b9e3f358174d58a584c2727b4     
n.恐龙( dinosaur的名词复数 );守旧落伍的人,过时落后的东西
参考例句:
  • The brontosaurus was one of the largest of all dinosaurs. 雷龙是所有恐龙中最大的一种。 来自《简明英汉词典》
  • Dinosaurs have been extinct for millions of years. 恐龙绝种已有几百万年了。 来自《简明英汉词典》
9 seismic SskyM     
a.地震的,地震强度的
参考例句:
  • Earthquakes produce two types of seismic waves.地震产生两种地震波。
  • The latest seismic activity was also felt in northern Kenya.肯尼亚北部也感觉到了最近的地震活动。
10 vibration nLDza     
n.颤动,振动;摆动
参考例句:
  • There is so much vibration on a ship that one cannot write.船上的震动大得使人无法书写。
  • The vibration of the window woke me up.窗子的震动把我惊醒了。
11 geologist ygIx7     
n.地质学家
参考例句:
  • The geologist found many uncovered fossils in the valley.在那山谷里,地质学家发现了许多裸露的化石。
  • He was a geologist,rated by his cronies as the best in the business.他是一位地质学家,被他的老朋友们看做是这门行当中最好的一位。
12 noted 5n4zXc     
adj.著名的,知名的
参考例句:
  • The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
  • Jim is noted for arriving late for work.吉姆上班迟到出了名。
13 bray hnRyv     
n.驴叫声, 喇叭声;v.驴叫
参考例句:
  • She cut him off with a wild bray of laughter.她用刺耳的狂笑打断了他的讲话。
  • The donkey brayed and tried to bolt.这头驴嘶叫着试图脱缰而逃。
14 craters 1f8461e3895b38f51c992255a1c86823     
n.火山口( crater的名词复数 );弹坑等
参考例句:
  • Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
  • The battlefield was full of craters made by exploding shells. 战场上布满弹坑。 来自《现代英汉综合大词典》
15 investigations 02de25420938593f7db7bd4052010b32     
(正式的)调查( investigation的名词复数 ); 侦查; 科学研究; 学术研究
参考例句:
  • His investigations were intensive and thorough but revealed nothing. 他进行了深入彻底的调查,但没有发现什么。
  • He often sent them out to make investigations. 他常常派他们出去作调查。

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