科学家称第二颗杀手小行星可能撞击地球

　　28 August 2022
　　科学家正在调查第二颗小行星与第一颗被认为杀死几乎所有恐龙的行星相同时间撞击地球的可能性。
　　该调查与最近在海洋口发现的火山口相关。
　　研究者认为火山口可能是由大行星创造。
　　科学家一直认为在6600百万年前在墨西哥
　　Yucatán半岛附近大行星撞击了地球。他们认为冲击强度相当于100亿个核弹。
　　冲击结果产生广泛山火，地震和海啸。科学家也相信产生大量化学物质到大气导致极寒天气。
　　气候变化导致70%以上的动植物消失。所有不像鸟的恐龙死了。
　　那次撞击的火山口是宽180千米深900米的大火山口。
　　研究人员说最新在北大西洋发现的火山口是很小的火山口。它宽约8.5千米。它被埋藏在西非几內亚海岸400米以下的海底。
　　科学家发现这个火山口是用地震仪发现的。这种仪器设计是测地震和地表的其它震动信号。
　　火山口由苏格兰(Uisdean Nicholson, a geologist at Heriot-Watt University in Edinburgh, Scotland)的Heriot-Watt大学的地理学家发现。
　　Scientists 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.
　　The investigation is linked to a smaller crater 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 tsunamis. 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 disappearance of more than 70 percent of plant and animal life. All dinosaurs 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 seismic instruments. Such tools are designed to measure earthquakes and pick up other  vibration  signals on Earth.
　　The 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.