On December 26, 2022, the solar wind round Mars all of the sudden “disappeared,” from the angle of NASA’s MAVEN orbiter. Because the solar wind density dropped, each Mars’ environment and magnetosphere swelled, increasing like a balloon for hundreds of kilometers. Video by way of NASA Goddard Space Flight Center.
The solar wind pours outward from our star at supersonic speeds. It’s a stream of charged particles, flowing via our solar system, buffeting the planets. More often than not, the solar wind is pretty regular. However on December 26, 2022, NASA’s MAVEN orbiter seen one thing odd. The solar wind round Mars all of the sudden “disappeared.” How was that attainable? On December 11, 2023, NASA said {that a} distinctive circumstance within the solar wind was accountable. And one thing else occurred, too. On account of the decreased solar wind, each Mars’ environment – the ionosphere, particularly – and magnetosphere expanded like a balloon, for hundreds of kilometers.
Jasper Halekas on the College of Iowa is the lead writer of a brand new peer-reviewed paper. He discussed the weird occasion and the science outcomes on the fall assembly of the American Geophysical Union (AGU23), held in San Francisco earlier this month.
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Mars and the solar wind
When the solar wind reaches Mars, it exerts strain on each the environment and magnetosphere. The wind hits the outer ionosphere portion of the environment, inflicting some particles to flee into space. It is a day by day incidence, for the reason that solar wind by no means stops.
Subsequently, Mars is all the time immersed within the solar wind, similar to the Earth and different planets. However what would occur if the solar wind did cease, or at the least diminish?
The day the solar wind disappeared at Mars
That’s precisely what occurred on December 26, 2022. For some cause, the solar wind all of the sudden decreased considerably. As Halekas said:
Once we first noticed the information, and the way dramatic the drop within the solar wind was, it was virtually unbelievable. We shaped a working group to check the occasion, and we’ve discovered this time interval to be wealthy with unbelievable findings.
MAVEN is exclusive in that it’s the solely orbiter that may concurrently observe each the sun’s exercise and the response of the Martian environment on the similar time. MAVEN’s devices detected many fewer particles within the solar wind than common hitting Mars on the time.
What brought on it?
So what brought on the solar wind to all of the sudden “disappear?” Mission scientists stated it was a singular solar occasion. Quicker-moving solar wind overtook slower-moving solar wind. This occasion – generally known as a stream interaction region – swept the 2 winds collectively, compressing them. The uncommon incidence subsequently left behind a void of low-density solar wind. That is what MAVEN noticed.
Mars’ environment swells like a balloon
However one thing else occurred, too. Because the solar occasion had created a void, there have been far fewer solar wind particles hitting Mars’ environment. The truth is, the density of the solar wind dropped by an element of 100. This meant much less strain being exerted on the environment. Consequently, each the ionosphere and magnetosphere tried to fill the void, increasing outward for hundreds of kilometers, like a balloon. General, they greater than triple their regular measurement.
As well as, the occasion even affected the sun’s magnetic area. Sometimes, it interacts with and is embedded inside Mars’ ionosphere. However when the solar wind decreased, the sun’s magnetic area was pushed outward. That, in flip, modified the ionosphere from magnetized to unmagnetized.
There’s additionally a layer between the solar wind and Mars’ magnetosphere. Throughout this occasion, it turned electromagnetically quiet.
A uncommon phenomenon
The solar wind has disappeared like this earlier than, however it’s an especially uncommon incidence. When it does occur, it’s when solar exercise on the sun will increase. Certainly, that is the primary time that MAVEN noticed this occurring because it arrived at Mars on September 21, 2014. Shannon Curry, principal investigator for MAVEN on the College of California, Berkeley, stated:
Observing excessive circumstances is all the time scientifically invaluable. MAVEN was designed to watch a lot of these interactions between the sun and the Martian environment, and the spacecraft supplied distinctive information throughout this really anomalous solar occasion.
The environment that Mars has now could be minuscule to what it used to have billions of years in the past. In 2015, MAVEN supplied extra proof that solar winds initially stripped the planet of most of its environment. Now, solely a really skinny remnant stays.
Certainly, MAVEN’s observations are serving to scientists higher perceive each the Martian environment and the sun. Gina DiBraccio is the MAVEN deputy principal investigatorat NASA’s Goddard Area Flight Heart in Greenbelt, Maryland. She stated:
This actually exhibits the cross-divisional function that MAVEN performs at Mars. MAVEN isn’t solely observing the dynamics of the Martian environment, it’s also monitoring solar inputs to boost our understanding of the sun.
Backside line: On December 16, 2022, the solar wind all of the sudden decreased at Mars. The uncommon occasion brought on the planet’s environment to swell outward like a balloon.
Source: The Day the Solar Wind Disappeared at Mars
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