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Scientists have announced that they managed to find an explanation for the appearance of a thin and rarefied atmosphere of the Moon. According to them, the main role in this process was played by evaporation after the fall of meteorites on the Earth's satellite, it is reported Live Science.
It is believed that the Moon has no atmosphere. But, although there is no breathable air on the Earth's satellite, it still has an atmosphere. But it is very thin and rarefied.
For a long time, scientists tried to explain the appearance of this atmosphere, which is also called the "exosphere". A new study showed that it appeared as a result of a powerful bombardment of the Moon by meteorites.
Moreover, scientists believe that it is this bombardment that has sustained the existence of the Moon's atmosphere for billions of years. Falling meteorites lift the lunar soil and cause vaporization of materials that either fly off into space or are trapped around the moon. Therefore, the exosphere of the Earth's satellite is renewed.
"We provide a definitive answer that meteorite impact evaporation is the dominant process creating the lunar atmosphere. The moon is about 4,5 billion years old, and during all this time the surface has been continuously bombarded by meteorites. We show that eventually the thin atmosphere reaches a steady state as it is continuously replenished by small shocks across the Moon," said lead study author Nicole Nee of the Massachusetts Institute of Technology (MIT).
At the beginning of its existence, the Solar System was very active, the surface of the Moon was constantly bombarded by impacts of large meteorites. Later, collisions between celestial bodies broke larger rocks. That is, over time, the bombardment of the Moon continued, but the meteorites falling on it became smaller and smaller. Micrometeorites the size of a grain of sand fell more and more frequently on Earth's satellite. But even the fall of small objects was enough for evaporation from impacts to maintain the atmosphere of the Moon.
Scientists assumed that the fall of space rocks on the surface of the Earth's satellite could be responsible for the appearance of its atmosphere, back in 2013. The LADEE probe then studied the Moon's thin atmosphere, surface conditions, and environmental effects on lunar dust. As a result, researchers were able to distinguish two processes that feed the atmosphere.
The first is impact vaporization, the second is "ion sputtering." The latter process occurs when high-energy charged particles from the Sun, known as the "solar wind," strike the surface of the Moon and transfer energy to the atoms. This effect also causes atoms to fly away into the atmosphere.
Nee and her colleagues wanted to determine which process is primarily responsible for maintaining the Moon's atmosphere. For this, they turned to lunar soil collected during the Apollo missions. As a result, they found that the key process responsible for the formation and maintenance of the Moon's atmosphere is evaporation caused by meteorite impacts.
