Long before the moon became the solid, crater covered orb we know today, it is said to have been covered with a massive ocean of molten magma.
Although the theory is widely accepted, how long the hot liquid remains uncertain among the scientific community – until now.
A new model suggests the ocean remained for 200 million years on the lunar surface before solidifying, which is 10 times longer than previously believed.
Astronomers looked at the low thermal conductivity of the lunar crust, along with heat extraction from rock particles in the magma to determine the life of the ocean.
During this investigation, the team also uncovered new evidence that proposes the moon may be 85 million years younger – an age closer that that of the Earth’s core.
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Long before the moon became the solid, crater covered orb we know today, it is said to have been covered with a massive ocean of molten magma. Although the theory is widely accepted, how long the hot liquid remains uncertain among the scientific community – until now
Scientists believe the moon formed when a Mars-sized protoplanet, dubbed Theia, collided with Earth about 4.5 billion years ago.
Theia hit Earth and caused the ejection of such a large amount of material from the planet’s mantle, which gathered to form the moon.
During this violent impact, a several-thousand-miles-deep magma ocean was created– however.
Researchers say the moon was ‘completely molten’ in its early years, and remained that way until rocks eventually floated to the surface and cooled.
Researchers say the moon was ‘completely molten’ in its early years, and remained that way until rocks eventually floated to the surface and cooled. The experts found found that the magma ocean was active 150 million to 200 million years ago
Researchers also determined that the moon is much younger than previously believed – by 85 million years. The team used a new numerical model to reconstruct the time at which the event occurred – 4.425 billion years ago. The previous assumptions about the formation of the Moon were based on an age of 4.51 billion years
Lead author Maxime Maurice, a planetary scientist at the German Aerospace Center in Berlin, told Space.com: ‘An important outcome of this scenario is that the early moon, which accreted from the debris of this giant impact, was very hot — hot enough for its rocky mantle to be largely molten and form what we call a magma ocean.’
In the new study, Maurice and his team designed a model that looked at the solidification of the magma ocean on the moon.
It included processes such as mantle convection, which is a low moving motion of Earth’s solid mantle caused by convection currents carrying heat from the inside to the surface and can be used when investigating the moon.
They found that the magma ocean was active 150 million to 200 million years ago.
Researchers also determined that the moon is much younger than previously believed – by 85 million years.
‘The results of our latest modeling suggest that the young Earth was hit by a protoplanet some 140 million years after the birth of the solar system 4.567 billion years ago,’ said Maurice.
‘According to our calculations, this happened 4.425 billion years ago—with an uncertainty of 25 million years—and the moon was born.’
They calculated how the composition of the magnesium- and iron-rich silicate minerals that formed during the solidification of the magma ocean changed over time.
The team discovered a dramatic change in the lunar composition of the remaining magma ocean as solidification progressed.
This finding is significant because it allowed the authors to link the formation of different types of rock on the moon to a certain stage in the evolution of its magma ocean.
Scientists believe the moon formed when a Mars-sized protoplanet, dubbed Theia, collided with Earth about 4.5 billion years ago. Theia hit Earth and caused the ejection of such a large amount of material from the planet’s mantle, which gathered to form the moon
Sabrina Schwinger, also involved with the study, said: ‘By comparing the measured composition of the moon’s rocks with the predicted composition of the magma ocean from our model, we were able to trace the evolution of the ocean back to its starting point, the time at which the moon was formed.’
The results of the study show that the moon was formed 4.425 billion years ago.
According to the scientists, the moon’s exact age is in remarkable agreement with an age previously determined for the formation of Earth’s metallic core with the uranium-lead method, the point at which the formation of planet Earth was completed.
Thorsten Kleine from the Institute of Planetology at the University of Münster, said: ‘This is the first time that the age of the moon can be directly linked to an event that occurred at the very end of the Earth’s formation, namely the formation of the core.’
SCIENTISTS DON’T AGREE ON HOW THE MOON FORMED BUT MANY BELIEVE IT WAS THE RESULT OF AN IMPACT BETWEEN EARTH AND ANOTHER PLANET
Many researchers believe the moon formed after Earth was hit by a planet the size of Mars billions of years ago.
This is called the giant impact hypothesis.
The theory suggests the moon is made up of debris left over following a collision between our planet and a body around 4.5 billion years ago.
The colliding body is sometimes called Theia, after the mythical Greek Titan who was the mother of Selene, the goddess of the moon.
Many researchers believe the moon formed after Earth was hit by a planet the size of Mars billions of years ago. This is called the giant impact hypothesis
But one mystery has persisted, revealed by rocks the Apollo astronauts brought back from the moon: Why are the moon and Earth so similar in their composition?
Several different theories have emerged over the years to explain the similar fingerprints of Earth and the moon.
Perhaps the impact created a huge cloud of debris that mixed thoroughly with the Earth and then later condensed to form the moon.
Or Theia could have, coincidentally, been chemically similar to young Earth.
A third possibility is that the moon formed from Earthen materials, rather than from Theia, although this would have been a very unusual type of impact.