Higher Perspective
A team of Harvard scientists believe the remnants of an ancient Earth, dating to the time another planet collided with ours to produce the moon, may still be lodged deep within the Earth’s mantle.
The team believes that a previously unexplained isotopic ratio from deep within the Earth might be a signal from material from before the Earth collided with another planet-sized body, which led to the creation of the Moon. This might be an echo of an ancient Earth that existed 4.5 billion years ago, prior to the proposed collision.
The current favored theory says that the Moon was formed 4.5 billion years ago when the Earth collided with a mass the size of Mars, dubbed “Theia.” This theory states that the heat generated by the collision would have melted the whole planet before some of the debris spun off to create the Moon.
But now, the team at Harvard, led by Associate Professor Sujoy Mukhopadhyay, believe that they’ve found evidence to support that only part of the Earth melted, and that an ancient part still exists within the Earth’s mantle.
According to Professor Mukhopadhyay: “The energy released by the impact between the Earth and Theia would have been huge, certainly enough to melt the whole planet. But we believe that the impact energy was not evenly distributed throughout the ancient Earth. This means that a major part of the impacted hemisphere would probably have been completely vaporized, but the opposite hemisphere would have been partly shielded, and would not have undergone complete melting.”
The team analyzed the ratios of noble gas isotopes from deep within the Earth’s mantle and compared the results to isotope ratios closer to the surface. They found that 3He to 22Ne ratio from the shallow mantle is significantly higher than the equivalent ratio deep within the mantle.
Professor Mukhopadhyay remarked: “This implies that the last giant impact did not completely mix the mantle and there was not a whole mantle magma ocean.”
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A team of Harvard scientists believe the remnants of an ancient Earth, dating to the time another planet collided with ours to produce the moon, may still be lodged deep within the Earth’s mantle.
The team believes that a previously unexplained isotopic ratio from deep within the Earth might be a signal from material from before the Earth collided with another planet-sized body, which led to the creation of the Moon. This might be an echo of an ancient Earth that existed 4.5 billion years ago, prior to the proposed collision.
The current favored theory says that the Moon was formed 4.5 billion years ago when the Earth collided with a mass the size of Mars, dubbed “Theia.” This theory states that the heat generated by the collision would have melted the whole planet before some of the debris spun off to create the Moon.
But now, the team at Harvard, led by Associate Professor Sujoy Mukhopadhyay, believe that they’ve found evidence to support that only part of the Earth melted, and that an ancient part still exists within the Earth’s mantle.
According to Professor Mukhopadhyay: “The energy released by the impact between the Earth and Theia would have been huge, certainly enough to melt the whole planet. But we believe that the impact energy was not evenly distributed throughout the ancient Earth. This means that a major part of the impacted hemisphere would probably have been completely vaporized, but the opposite hemisphere would have been partly shielded, and would not have undergone complete melting.”
The team analyzed the ratios of noble gas isotopes from deep within the Earth’s mantle and compared the results to isotope ratios closer to the surface. They found that 3He to 22Ne ratio from the shallow mantle is significantly higher than the equivalent ratio deep within the mantle.
Professor Mukhopadhyay remarked: “This implies that the last giant impact did not completely mix the mantle and there was not a whole mantle magma ocean.”
Read more
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