The magnetic field of the new moon could serve as an additional barrier that protected The earth's atmosphere from being blown away by the solar wind. This conclusion was reached by scientists from NASA, who conducted computer simulations of the interaction of the earth's magnetospheres and the moon. The article is published in the journal Science Advances.
The habitability of planets depends on many factors, including the presence of a constant and sufficiently strong magnetic field. It is generated by the movement of liquid in the planet's red-hot core (this is called the Dynamo effect) and helps keep the atmosphere from escaping into space under the influence of a stream of charged particles coming from the stars.
Current research suggests that The earth's magnetic field existed at least 3.5 billion years ago, and bolder estimates suggest that 4.2 billion years ago. However, as models show, it was about half as weak as today, and little is known about its behavior in the past. At the same time, the young Sun, despite its lower brightness, should have experienced powerful enough flashes that could destroy the gas envelope of our planet. However, even in these conditions, the Earth was able to preserve the atmosphere.
The moon's magnetic field could help it do this, according to James Green of NASA and his colleagues. Today, the moon does not have a dipole field, but it has not always been so. For a long time, its interior remained hot, which allowed the Dynamo effect to occur, and traces of this process were preserved in samples of local rocks. It is estimated that between 4.25 and 3.5 billion years ago, the moon's magnetic field induction ranged from 20 to 100 microtesla, and 3.2 billion years ago, this value fell to 5 microtesla.
In addition, in the past, the Moon was much closer to the Earth, only 130 thousand kilometers (for comparison, today the distance is 385 thousand kilometers), which allowed the magnetic fields of the two celestial bodies to interact. In the new paper, the scientists looked at what exactly this interaction could be and how it affected the Earth, and conducted simulations of the interaction of the earth's magnetosphere and the moon.
Simulations have shown that the lines of force of The earth's magnetic fields and the moon could connect — mostly at high and middle latitudes. This interaction could serve as an additional shield for the Earth's atmosphere and help reduce the loss of ionospheric plasma, creating a kind of "protective magnetic bubble". In addition, along the lines of force, atmospheric components could be exchanged between our planet and a young satellite, where volcanism still persisted. This could explain the presence of nitrogen and some other inert gases in the lunar regolith.
The team hopes that new samples obtained during lunar missions will provide more information. Of particular interest are the so-called "cold traps" at the satellite's poles. They are reliably protected from the Sun and can store oxygen and nitrogen obtained from the Earth's atmosphere.
Previously, scientists concluded that the lunar magnetic field disappeared a billion years later than previously thought. It could have existed even 2.5 billion years ago.