Moon shielding was crucial to Earth’s ability to sustain its atmosphere

Earth and Moon Galileo Composite

The combination of the two images from the 1990s Galileo mission shows a long shared history of the Earth and the Moon shown here. Billions of years ago, they were connected to magnetic fields. Credit: NASA / JPL / USGS

The Earth and the Moon once share a magnetic shield, protecting their atmosphere

Four and a half billion years ago, the earth’s surface was a frightening, hot mess. Long before the emergence of life, the temperature was blazing, and the air was toxic. Plus, just as a toddler, the sun attacked our planet with a furious fury of radiation with fires and coronal mass ejections. Streams of charged particles known as solar winds endanger our atmosphere. Our planet, in short, was unsustainable.

But the neighborhood can help our planet maintain its atmosphere and ultimately develop life and livable conditions. It was ield the moon, he says NASA-Study in the journal Science progress.

Lines of the Earth's magnetic field

This picture shows the lines of the magnetic field that the earth produces today. The moon is no longer a magnetic field. Credit: NASA

Jim Green, NASA’s chief scientist and lead author of the new study, said the moon represents a significant protective barrier against solar wind for the Earth, which was crucial to the Earth’s ability to maintain the atmosphere during this time. “We look forward to advancing these findings when NASA sends astronauts to the moon through the Artemis program, which will return crucial samples to the lunar South Pole.”

A brief history of the moon

Billion formation of the moon. billion billion years ago when a MarsAccording to leading theories, when our planet was less than 100 million years old, an object object the size of Thea collapsed into proto-Earth. Debris from the collision rejoined the moon, while other remnants reconnected themselves to Earth. Due to gravity, the presence of the moon stabilized the Earth’s spin axis. At that time, our planet was spinning very fast, with only 5 hours running a day.

And in the early days, the moon was also very close. As the moon’s gravity pulls over our oceans, the water heats up a little, and that energy is lost. As a result, the moon moves away from the earth every year at a rate of 1.5 inches or the width of two nearby dimes. Over time, that really adds up. 4 billion years ago, the Moon was three times closer to Earth than it is today – about 80,000 miles away from the current 238,000 miles. At some point, even the moon is “locked by the tide,” meaning the earth looks at one side of it.

Lunar magnetic field

When the moon has a magnetic field, it is protected from incoming solar winds, as shown in this picture. Credit: NASA

Scientists once thought that the moon never had a lasting magnetic field because it had such a small core. Due to the magnetic field the electric charge travels along invisible lines, tilting towards the moon at the poles. Scientists have long known about the Earth’s magnetic field, creating beautiful colored auroras in the Arctic and Antarctic regions.

The magnetic field serves as a means by which the electric charge moves along its invisible lines. Scientists have long known about the Earth’s magnetic field, which causes beautiful colored auroras in the Arctic and Antarctic regions. The motion of liquid iron and nickel inside the earth, which flows due to the heat remaining from the earth’s formation, produces magnetic fields that create protective bubbles around the earth, the magnetosphere.

But thanks to the Apollo mission’s study of lunar surface samples, scientists have discovered that the moon once had a magnetosphere. Evidence continues to grow from samples that have been sealed for decades and recently analyzed by modern technology.

Like Earth, the heat from the formation of the moon would have kept iron in a deep stream, although not for long due to its size.

“It’s like baking a cake: you take it out of the oven, and it’s still cooling,” Leela said. “The bigger this mass, the longer it will take to cool down.”

A magnetic ield

The new study mimics how the Earth and the Moon’s magnetic field behaved about a billion billion years ago. Scientists created a computer model to observe the behavior of the magnetic field at two locations in their respective orbits.

Earth and lunar magnetic fields

This illustration shows how both the Earth and its moon had magnetic fields that were connected billions of years ago, helping to protect their atmosphere from the currents of harmful solar particles, according to new research. Credit: NASA

At certain times, the moon’s magnetosphere would have acted as a barrier to the harsh solar radiation falling on the Earth-Moon system, scientists write. This is because, according to the model, the magnetic field of the Moon and the Earth would be magnetically connected to the polar regions of each of the objects. Importantly, for Earth’s evolution, high-energy solar wind particles cannot fully penetrate the attached magnetic field and rob the atmosphere.

But there was also some atmospheric exchange. Extreme ultraviolet light from the sun would strip electrons from neutral particles in the Earth’s upper atmosphere, charge the particles, and travel to the moon along the lunar magnetic field lines. At this point, the moon may contribute to maintaining a thinner atmosphere. The discovery of nitrogen in lunar rock samples supports the idea that the Earth’s atmosphere, which is dominated by nitrogen, contributes to the Moon’s ancient atmosphere and its crust.

Scientists have calculated the position of this shared magnetic field connected to the Earth and Moon’s magnetic spheres, 1.1 to 3.5. could have lived billions of years ago.

“Understanding the history of the Moon’s magnetic field helps us understand not only the possible initial atmosphere, but also how the Moon developed internally,” said David Draper, NASA’s Deputy Chief Scientist and study co-author. “It tells us what the origin of the moon could be – a combination of both liquid and solid metal at some point in its history – and is a very important part of the puzzle for how it works on the inside of the moon.”

Over time, as the moon’s interior cools, our nearest neighbor lost its magnetosphere and eventually its atmosphere. There must have been a significant decline in this area 3.5 billion years ago and about 1 billion. It disappeared 1.5 billion years ago. Without a magnetic field, the solar wind strips the atmosphere. That’s why Mars lost its atmosphere: solar radiation stripped it.

Similarly, if our moon played a role in shielding our planet from harmful radiation at the time of a serious planet, similarly, the galaxy may have other moons around terrestrial exoplates that help maintain the atmosphere for their host planets, and also contribute to habitation. Scientists say. This will be of interest in the field of astrobiology – the study of the origins of life and the discovery of life beyond Earth.

Human research can tell us more

This modeling study presents ideas for how the ancient history of the Earth and the Moon contributes to maintaining the Earth’s early atmosphere. Mysterious and complex processes are difficult to unravel, but new specimens from the lunar surface will reveal the secrets.

As NASA plans to establish a sustainable human presence on the moon through the Artemis program, there could be many opportunities to test these ideas. When astronauts return the first samples from the Moon’s South Pole, where the Earth and the Moon’s magnetic fields are very strongly connected, scientists can find chemical signatures of the Earth’s ancient atmosphere, as well as volatile objects such as water that were delivered by impacting meteors. And asteroids. Scientists are particularly interested in areas of the Moon’s South Pole that have not seen any sunlight for billions of years – “permanent shaded regions” – because hard solar particles would not have been unstable.

Nitrogen and oxygen, for example, can travel from the earth to the moon along magnetic field lines and are trapped in rocks.

“In order to be able to undo this initial evolution of the Earth’s instability, we need critical samples of permanently shaded regions,” Green said.

Reference: “When the Moon had a Magnet Osphere”, by James Green, David Draper, Scott Bordsen and Chuanfei Dong, 14 October October 2020, Science progress.
DOI: 10.1126 / sciadv.abc0865

Other co-authors on paper are Scott Bordsen of the University of Maryland, Baltimore County; And from Chuanfei Dong Princeton University In New Jersey.