Mars experienced a sudden rupture in the cosmic order about one year ago. The red planet looked like it had been temporarily transported to another solar systems.
Normally in our solar system, the sun is constantly spewing out a stream of charged particles and magnetic fields, called the solar wind.
This wind washes over the planets and exerts pressure on them that helps hold in their atmospheres. The aurorae, the beautiful northern lights seen on Earth often are also created by this wind.
In December 2022, though, the solar wind suddenly disappeared around Mars, and the planet’s atmosphere swelled by thousands of kilometers, as a result.
NASA’s MAVEN spacecraft, which orbits Mars, observed the whole thing. The scientists announced the findings about this event on Monday at the Fall Meeting of the American Geophysical Union in San Francisco.
An eruption on the sun swept away the solar wind
Scientists determined that the sun had emitted a burst of high-speed solar wind, which swept away a region of the regular solar wind, leaving a void in its wake.
“Each solar storm is different, but this one is extra different,” Shannon Curry, principal investigator of the MAVEN mission, said in the briefing.
At Mars, according to MAVEN’s data, there was virtually no solar wind — the density of solar particles had dropped by a factor of 100. Mars’s atmosphere swelled by thousands of kilometers, as a result.
This unusual type of phenomenon was last seen in 1999, when a NASA satellite observed the solar wind effectively disappear around Earth, causing our own planet’s atmosphere to swell five times larger than normal, the NASA scientists said.
The mysterious event may offer clues in the search for alien life
NASA scientists jumped to study this rare, extreme event for a few reasons.
Curry said that “solar event will be very important for understanding human exploration of Mars.”
That’s because Earth’s atmosphere protects us from the sun’s shenanigans, but astronauts in space are vulnerable to the extreme radiation that can come with solar eruptions.
NASA plans to send people to Mars one day, which will put them in an extended window of exposure to the solar wind and radiation. The journey would take a total of two to three years, Popular Science has reported. For comparison, NASA astronauts typically only stay on the International Space Station for six months and the longest human spaceflight on record was 437 days.
The vanishing solar wind also offers a clue as to how Mars became such a dry, harsh, lifeless place.
The planet was once awash with water. Scientists suspect that there could have been microbial life on Mars at the time. Mars’s atmospheric layer deteriorated into outer space and eventually left it too exposed to be able to support liquid water.
Curry said that powerful barrages of solar wind may have eroded away the Martian atmosphere. It’s helpful to look at the other extreme: when solar winds disappear.
There’s another alien-life motive to understand the disappearance of the solar wind: The event offers a peek at how rocky planets might look around other, less windy stars.
Mars’s magnetic profile changed, too
The solar wind also interacts with the planet’s upper atmosphere to form its magnetosphere — the region of space where Martian magnetic fields dominate.
The magnetosphere around Mars is similar to Earth’s bubble, which the solar winds must pass through.
But as the solar wind disappeared the magnetosphere expanded outward and engulfed the MAVEN orbit.
As quickly as the solar wind disappeared on December 25, 2022, however, it was back by December 27, 2022, and Mars’s atmosphere and magnetosphere shrank back to their regular proportions.
As the sun gets more active, more rare events like this can happen
The sun is nearing the peak of its 11-year cycle, which means that its bubbling plasma surface is forming more sunspots and emitting more eruptions, floods of solar wind, and other extreme events.
On Earth we are aware that solar storms and eruptions can cause aurorae and magnetic havoc, which interferes with compasses. They also have the potential to disrupt radio and power grids.
In the next year, as the sun’s activity continues to ramp up to its peak, NASA’s MAVEN mission may have even more opportunities to study such solar outbursts from the Martian perspective.