Relics of Huge Primordial Collision Reside in Earth’s Deep Interior

Context:

• In a groundbreaking study, scientists have proposed that the mysterious “blobs” deep within Earth’s mantle are actually remnants of a protoplanet named Theia.

Theia and Earth’s Collision

• Theia is theorized to have collided with Earth around 4.5 billion years ago, an event that not only led to the formation of the Moon but also left behind parts of Theia near Earth’s core. 

Key Findings of Study

• Seismologists have recognized  since the 1970s that two mysterious continent-sized blobs reside in the deepest part of Earth’s mantle, one under Africa and the other under the South Pacific region.
• These blobs, denser than the material surrounding them, may be relics from a cataclysm early in our planet’s history hypothesized to have spawned the moon – the collision between primordial Earth and a Mars-sized object called Theia.
• The researchers ran computer simulations examining the impact event, geophysical properties of the material that likely made up Theia and the evolution of Earth’s mantle – the broadest of the layers that comprise our planet’s interior structure at about 1,800 miles (2,900 km) thick.
• Based on these simulations, they proposed that most of Theia was absorbed into Earth, forming the blobs, while residual debris formed the moon
• The bottoms of these blobs are 2,900 kilometers below our feet. The two blobs are about 2% of Earth’s mass. 
• If the study’s conclusions are correct, these blobs would represent elusive evidence right here on Earth of the hypothesized moon-forming collision.

News Source: The Hindu