The Martian atmosphere was once as thick as the Earth today, but now it is invisible. This is mainly because the internal structure of Mars cannot form a complete magnetosphere to protect the atmosphere, and the latter has been stripped away by the solar wind over the years. But last December, the solar wind “disappeared” for two days due to fate, causing the sunward atmosphere of Mars to immediately expand to four times its usual size. This is very valuable information for understanding the evolution history of Mars.
The solar wind (olar wind) is an ultra-high-speed plasma (charged particle) flow emitted from the upper atmosphere of the sun. It travels throughout the solar system and even reaches Pluto. NASA’s MAVEN Mars orbiter has been observing the Martian atmosphere and them since 2014. How to respond to the various behaviors of the sun.
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Last Christmas, for the first time in its ten-year career, the MAVEN probe detected an atypical event in which the solar wind suddenly completely disappeared near Mars.
Mars, like other planets in the solar system, is constantly blown by the solar wind throughout its life. Unfortunately, Mars does not have a magnetic field to protect itself. Therefore, the solar wind has continuously driven the Martian atmosphere to escape for billions of years, resulting in the desolate environment of Mars today.
However, the planet’s atmosphere changes so dynamically that a special type of solar event broke out in December 2022, causing the faster-moving solar wind to jump over the slower-moving solar wind. The former was like a broom compressing the two regions and forming a rare “vacuum” in the wake. ” area, arriving near Mars around Christmas last year, MAVEN was lucky enough to observe this phenomenon.
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MAVEN measurements showed that the number of particles making up the solar wind dropped significantly at that time (the density dropped by 100 times). After the pressure of the solar wind was reduced, astronomers even witnessed the expansion of the Martian atmosphere and magnetosphere by thousands of kilometers. It was simply the best Christmas gift.
Observing this dramatic event and the subsequent transformation of the entire system can allow scientists to better understand the physical principles that lead to the loss of Mars’ atmosphere and water. As the sun approaches its maximum activity, MAVEN may help us see how extreme solar events affect the Martian atmosphere. This new aspect also helps us understand how Earth-like planets outside the solar system interact with their host stars.
(Source of first picture:NASA）
