Scientists: Evidence of Crash with Another Planet under Earth's Surface
2023-11-13
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1Scientists have recognized since the 1970s that there are two large, mysterious blobs in the deepest part of Earth's mantle.
2One of the masses is under Africa and the other under the South Pacific Ocean.
3Recent research suggests these masses, which are denser than the material surrounding them, might be from a huge crash early in our planet's history.
4Researchers recently said the crash between Earth and a Mars-sized object called Theia might have created the moon.
5Recent research suggests the event happened more than 4.46 billion years ago.
6Pieces of Theia, however, might have remained inside Earth, sinking to an area just above our planet's hot core of iron and nickel.
7Researchers created computer simulations to study their theory of the event.
8Based on these simulations, they proposed that most of Theia was absorbed into Earth, forming the two masses, while the remaining pieces formed the moon.
9Qian Yuan is a geophysicist at Caltech and the lead writer of the study that was published recently in Nature.
10"The bottoms of these blobs are 2,900 kilometers below our feet.
11The two blobs are about 2 percent of Earth's mass.
12They were detected by seismology as seismic waves travel slower within these two regions compared to the surrounding mantle.
13Each of the blobs are twice the mass of the whole moon. So, the blobs are massive," Yuan said.
14If the theory is correct, these two masses would represent evidence of the possible moon-forming crash.
15Caltech professor and study co-writer Paul Asimow said there has not been agreement "on whether we can find evidence for this event not just in the moon but also in some observable property of the modern Earth."
16The two masses, Asimow added, are the biggest difference "in Earth structure from a simple layered planet."
17Study co-writer Hongping Deng of the Chinese Academy of Sciences' Shanghai Astronomical Observatory said, "It is incredible because we can uncover relics of another planet - Theia - if we dig deep enough in Earth's mantle."
18The increased density of the masses is believed to come from their high level of iron. Moon rocks also contain high iron levels.
19So, the researchers think it would make sense if they came from the same place: Theia.
20The moon, which orbits Earth at an average distance of about 385,000 km, has a diameter of about 3,475 km, a bit more than a quarter of our planet's diameter.
21Asimow said that, if the theory is correct, some volcanic rocks that reach Earth's surface might provide pieces of Theia.
22"If our model is correct, the blobs should have isotopes - trace elements - that are similar to the lunar mantle rocks, which can be tested in future lunar missions," Yuan said.
23Gaining a greater understanding of the hypothesized giant impact could provide information concerning the evolution of Earth and other rocky planets in our solar system and beyond it.
24"Earth is still the only confirmed habitable planet, and we do not know why," Yuan said.
25He added the crash set the early conditions for Earth's development and said: "Studying its consequences may help us to figure out why Earth is different than other rocky planets."
26I'm John Russell.
1Scientists have recognized since the 1970s that there are two large, mysterious blobs in the deepest part of Earth's mantle. 2One of the masses is under Africa and the other under the South Pacific Ocean. 3Recent research suggests these masses, which are denser than the material surrounding them, might be from a huge crash early in our planet's history. 4Researchers recently said the crash between Earth and a Mars-sized object called Theia might have created the moon. 5Recent research suggests the event happened more than 4.46 billion years ago. Pieces of Theia, however, might have remained inside Earth, sinking to an area just above our planet's hot core of iron and nickel. 6Researchers created computer simulations to study their theory of the event. Based on these simulations, they proposed that most of Theia was absorbed into Earth, forming the two masses, while the remaining pieces formed the moon. 7Qian Yuan is a geophysicist at Caltech and the lead writer of the study that was published recently in Nature. 8"The bottoms of these blobs are 2,900 kilometers below our feet. The two blobs are about 2 percent of Earth's mass. They were detected by seismology as seismic waves travel slower within these two regions compared to the surrounding mantle. Each of the blobs are twice the mass of the whole moon. So, the blobs are massive," Yuan said. 9If the theory is correct, these two masses would represent evidence of the possible moon-forming crash. 10Caltech professor and study co-writer Paul Asimow said there has not been agreement "on whether we can find evidence for this event not just in the moon but also in some observable property of the modern Earth." 11The two masses, Asimow added, are the biggest difference "in Earth structure from a simple layered planet." 12Study co-writer Hongping Deng of the Chinese Academy of Sciences' Shanghai Astronomical Observatory said, "It is incredible because we can uncover relics of another planet - Theia - if we dig deep enough in Earth's mantle." 13The increased density of the masses is believed to come from their high level of iron. Moon rocks also contain high iron levels. So, the researchers think it would make sense if they came from the same place: Theia. 14The moon, which orbits Earth at an average distance of about 385,000 km, has a diameter of about 3,475 km, a bit more than a quarter of our planet's diameter. 15Asimow said that, if the theory is correct, some volcanic rocks that reach Earth's surface might provide pieces of Theia. 16"If our model is correct, the blobs should have isotopes - trace elements - that are similar to the lunar mantle rocks, which can be tested in future lunar missions," Yuan said. 17Gaining a greater understanding of the hypothesized giant impact could provide information concerning the evolution of Earth and other rocky planets in our solar system and beyond it. 18"Earth is still the only confirmed habitable planet, and we do not know why," Yuan said. He added the crash set the early conditions for Earth's development and said: "Studying its consequences may help us to figure out why Earth is different than other rocky planets." 19I'm John Russell. 20Will Dunham reported on this story for Reuters. John Russell adapted it for VOA Learning English. 21__________________________________________________ 22Words in This Story 23blob -- n. (informal) something that does not have a regular shape 24mantle -- n. the middle layer of the Earth that is between the top crust and the inner core 25core -n. the central part of something, such as the Earth 26simulation -- n. something that is made to look, feel, or behave like something else 27absorb -v. to take in some substance, especially a liquid 28seismology -- n. the scientific study of earthquakes 29relic -- n. something that is from a past time or place 30isotope -- n. any one of various forms of the same chemical element 31trace -adj. existing in small amounts 32habitable -adj. able to be lived in; able to support life 33consequences -n. (pl.) the results of an event or a decision