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Scientists thrilled after Mars’ atmosphere swells up like a balloon for this strange reason

Scientists thrilled after Mars’ atmosphere swells up like a balloon for this strange reason

It was a rare and exciting Martian event.

Mars, our mysterious red neighbor, has been throwing some cosmic curveballs at scientists, and their latest discovery has left them buzzing with excitement.

The entire planet's atmosphere was found to expand like a balloon, not because of an alien encounter or a natural disaster, but due to a pause in the solar wind. This occurrence on Mars isn't just a fascinating anomaly, it's a scientific marvel.

Typically, Mars' atmosphere is under constant assault by the solar wind, a relentless stream of charged particles from the sun. This solar barrage reportedly strips away about 0.25 lbs (0.11 kg) of the Martian atmosphere every second. Scientists believe this is making Mars' atmosphere leak into space.


However, in a surprising twist, for two days last December, the solar wind just... stopped.

This sudden break caused Mars' atmosphere on its sun-facing side to balloon to nearly four times its usual size, according to, growing from 497 miles (800 km) to over 1,864 miles (3,000 km).

Captured by NASA's MAVEN (short for Mars Atmosphere and Volatile EvolutioN) orbiter - which has been observing Mars' atmosphere since 2014 - this phenomenon wasn't just a blip on the radar; scientists are heralding it as historic.

"When we first saw the data, and how dramatic the drop in the solar wind was, it was almost unbelievable," said Jasper Halekas, professor at the University of Iowa and the lead author on a new study on the event.

"We formed a working group to study the event, and we have found this time period to be rich with incredible findings."

The findings were announced at the AGU conference this week in California, with MAVEN's data showing that not only Mars’ atmosphere but also the magnetosphere and ionosphere expanded in this unusual event.

So why is this swelling of Mars' atmosphere a big deal?

It's not just about breaking records or witnessing a rare cosmic event. This unusual episode occurred after a fast-moving region of solar wind overtook its slower counterpart, creating a sparse region that reached Mars on Christmas Day 2022.

Ales_Utovko / Getty

"We are really getting to see how Mars responds when the solar wind is effectively removed," Halekas said. "It makes for a great outlier study on what Mars would be like if it were orbiting a less ‘windy’ star."

Two days after the storm passed Mars, the planet's atmosphere settled down. However, the insights from MAVEN's data have implications beyond just Mars. The researchers believe that they could offer a window into the atmospheric dynamics of Earth-like planets orbiting other stars. reports MAVEN team member Skylar Shaver of the Laboratory for Atmospheric and Space Physics in Boulder as saying: "We could look under the hood at what physics is going on, how the dynamics are working and really get a sense of those details."

And although extraordinary, scientists suggest this might not be the first time it has happened.

Shannon Curry, the principal investigator for the MAVEN mission, reportedly suspects these kinds of events were common on Mars around three to four billion years ago - potentially explaining how it went from a potentially watery and life-supporting planet to the dusty lifeless world we know today.

Featured Image Credit: Credit: Baac3nes / Ales_Utovko / Getty