2023-08-08 23:54:57
During periods of maximum activity, the Sun from time to time dumps the accumulated excess energy. This can occur in the form of bursts of radiation or large-scale ejections of matter from the outer layers of the star – coronal mass ejections. Plasma flows can gain mass of millions and billions of tons, accelerate to hundreds and thousands of kilometers per second. Reaching the Earth, coronal mass ejections cause geomagnetic storms and the appearance of auroras. The largest of them can “cover” colossal spaces, as the event of October 28, 2021 showed. Then the ejection was registered by instruments that worked not only in near-Earth orbit, but also on the Moon and even on Mars, which at that moment was on the other side of the Sun from us. This is described in an article published in the journal Geophysical Research Letters. The ejection was accompanied by an increase in the ground level of cosmic ray intensity. This shows that its energy turned out to be enough for the charged particles of the plasma not only to be deflected by the magnetic field of our planet, but to “pierce” it through and through. In the entire history of observations, which began back in the 1940s, less than a hundred such events have been recorded. The Moon and Mars do not have a global magnetic field (and the Moon does not have an atmosphere), so CME plasma reaches their surface unhindered. The doses of radiation that the 2021 emission brought remained at a safe level / ©ESA, CC BY-SA 3.0 IGO the ExoMars TGO probe operating in Martian orbit and the Curiosity rover. Moreover, the Earth and Mars were on opposite sides of the Sun, and the distance between them was regarding 250 million kilometers. In addition, the ejection was noticed by Solar Orbiter, SOHO and BepiColombo working closer to the Sun. The dose of radiation registered in the orbit of our planet was 10 milligray, on the circumlunar – 31 milligray, near Mars – nine milligray. Note that 700 milligray can cause serious health problems, and the deadly value is 10 gray (10 thousand milligray). In this case, the dose accumulates over time. “Our estimates of past events with an increase in the ground level of cosmic ray intensity suggest that, occurring once every 5.5 years, they are able to overcome the permissible threshold on the Moon if people are there without special protection,” said Jinan Guo ( Jingnan Guo, one of the authors of the new work.
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