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The Mysterious Continent-sized Blobs in Earth’s Mantle: Remnants of a Moon-forming Collision
An artist’s impression shows a Mars-sized object colliding with primordial Earth in the “Giant Impact”, hypothesized as the event that resulted in the formation of the Moon, with an “after” view of the interior of the Earth showing remnants of the impactor at the bottom of the Earth’s mantle, in this undated handout image. | Photo Credit: Reuters
Significance and Features of the Continent-sized Blobs
Seismologists have discovered two continent-sized blobs within the deepest part of Earth’s mantle, one beneath Africa and the other beneath the South Pacific region. These dense blobs differ in composition from the surrounding material and are believed to be remnants of a cataclysmic event that occurred in the early stages of Earth’s formation – the collision between primordial Earth and a Mars-sized object called Theia.
Objectives and Effects
The researchers conducted computer simulations to better understand the impact event, the geophysical properties of Theia, and the evolution of Earth’s mantle. Based on their findings, they propose that most of Theia was absorbed into Earth, creating the continent-sized blobs. The residual debris from the collision formed the Moon. These findings provide evidence within Earth itself that supports the theory of a moon-forming collision.
Pros and Cons
The discovery of the continent-sized blobs brings us closer to understanding the unique origins and evolution of Earth. By studying the consequences of this giant impact, scientists hope to gain insights into why Earth is different from other rocky planets in our solar system. However, as with any scientific theory, further research and evidence are necessary to corroborate these findings fully.
Fun Fact
If the researchers’ conclusions are accurate, volcanic rocks reaching Earth’s surface could provide samples from a vanished planet, offering scientists an opportunity to examine trace elements and isotopes that are similar to the lunar mantle rocks. This could be further explored in future lunar missions.
Gaining a greater understanding of the hypothesized giant impact may not only shed light on Earth’s evolution, but also provide valuable insights into the development of other rocky planets within our solar system and beyond.
“Earth is still the only confirmed habitable planet, and we do not know why,” says Caltech geophysicist Qian Yuan, lead author of the study. “This collision likely set the initial condition of Earth’s evolution. Studying its consequences may help us to figure out why Earth is different than other rocky planets.”
Mutiple Choice Questions
1. Seismologists have discovered two mysterious continent-sized blobs residing in which part of Earth?
a) Crust
b) Mantle
c) Core
d) Lithosphere
Answer: b) Mantle
Explanation: Seismologists have identified two large blobs in the deepest part of Earth’s mantle, one under Africa and the other under the South Pacific region.
2. What is the hypothesized cause of the formation of these blobs?
a) Volcanic eruptions
b) Plate tectonics
c) Giant impact
d) Continental drift
Answer: c) Giant impact
Explanation: Recent research suggests that these blobs are remnants of a giant impact between primordial Earth and a Mars-sized object called Theia, which resulted in the formation of the Moon.
3. How long ago did the collision between Earth and Theia occur?
a) 4.46 million years ago
b) 4.46 billion years ago
c) 4.46 trillion years ago
d) 4.46 quadrillion years ago
Answer: b) 4.46 billion years ago
Explanation: Recent research has determined that the giant impact between Earth and Theia took place more than 4.46 billion years ago.
4. Where did most of Theia go after the collision?
a) The surface of the Earth
b) The Earth’s core
c) The Moon
d) The Earth’s mantle
Answer: d) The Earth’s mantle
Explanation: Computer simulations suggest that most of Theia was absorbed into Earth’s mantle, forming the continent-sized blobs that are currently observed.
5. How do seismologists detect the presence of these blobs in the mantle?
a) By measuring temperature differences
b) By studying volcanic activity
c) By analyzing seismic waves
d) By examining magnetic field variations
Answer: c) By analyzing seismic waves
Explanation: The blobs can be detected by analyzing seismic waves, which travel slower through these regions compared to the surrounding mantle.
6. What is the mass of each of these blobs compared to the Moon?
a) Half the mass of the Moon
b) Equal to the mass of the Moon
c) Twice the mass of the Moon
d) Ten times the mass of the Moon
Answer: c) Twice the mass of the Moon
Explanation: Each of the blobs has a mass that is twice the mass of the Moon, making them significantly massive compared to the Moon.
7. What property of the Earth do these blobs represent?
a) Volcanic activity
b) Plate tectonics
c) Deviation from a simple layered structure
d) Magnetic field variations
Answer: c) Deviation from a simple layered structure
Explanation: The blobs are the biggest deviations in Earth’s structure from a simple layered planet, according to Professor Paul Asimow.
8. What elements are thought to contribute to the increased density of these blobs?
a) Oxygen and nitrogen
b) Silicon and aluminum
c) Iron and nickel
d) Hydrogen and helium
Answer: c) Iron and nickel
Explanation: The increased density of the blobs is believed to arise from their high content of iron, which is similar to moon rocks.
9. How can the hypothesis of the giant impact between Earth and Theia be further tested?
a) By studying volcanic rocks on the Moon
b) By analyzing meteorites from Mars
c) By drilling deep into the Earth’s mantle
d) By examining lunar missions
Answer: d) By examining lunar missions
Explanation: Future lunar missions could provide samples of the lunar mantle rocks, allowing for isotopic testing to confirm the connection between the blobs and the Moon.
10. Why is studying the giant impact and its consequences important?
a) It explains the origin of volcanic activity on Earth.
b) It helps understand the evolution of other rocky planets.
c) It reveals the reasons for the Earth’s habitable conditions.
d) It provides insights into the formation of Earth’s core.
Answer: b) It helps understand the evolution of other rocky planets.
Explanation: Studying the giant impact and its consequences can provide valuable insights into the evolution of not only Earth but also other rocky planets in our solar system and beyond.
Brief Summary | UPSC – IAS
Seismologists have discovered two large blobs in the deepest part of Earth’s mantle that could be remnants of a collision between Earth and a Mars-sized object, known as Theia, that formed the moon. Computer simulations showed that most of Theia was absorbed into Earth, forming the blobs, while residual debris coalesced to create the moon. The dense blobs are believed to be made up of material from Theia and have a higher iron content, similar to moon rocks. Scientists hope that further study of these blobs could provide insights into the evolution of Earth and other rocky planets.