A Martian Thriller May Lastly Be Solved

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While this picture may appear like streaks of mascara absentmindedly left on a pillow, you’re really glimpsing what seems to be the aftermath of mud avalanches on Mars.

Sometime between 2013 and 2017, a meteoroid slammed into the sting of Apollinaris Mons, a large historic volcano. Fine mud then cascaded down steep slopes of the crater and fashioned the darkish streaks seen on this picture, which was captured by the European Space Agency’s ExoMars Trace Gas Orbiter on Christmas Eve in 2023.

But it’s not the one such assortment of those darkish streaks on the Red Planet’s floor. More than 2 million streaks appear to exist round its globe, based on a new Nature Communications study by Valentin Tertius Bickel, a planetary geomorphology researcher on the University of Bern’s Center for Space and Habitability in Switzerland. According Bickel’s evaluation of streak photos, they not often appear to end result from dramatic occasions, akin to meteoroid impacts and marsquakes. Instead, usually, these streaks seem to emerge from one thing way more mundane: The seasons.

Read extra: “Do Our Oceans Feel the Tug of Mars?”

In Mars’ southern summer season and autumn, it will get windy sufficient to knock loads of sand round. And at varied spots on Mars, probably the most intense wind stresses appear to happen round dawn and sundown. This may clarify why scientists have not often seen these streaks kind, as a result of most Mars orbiters aren’t able to capturing photos at these dimmer instances. These streaks additionally are inclined to fade after a couple of years or a long time.

The new research additionally provides to rising proof that the streaks aren’t related to liquid water on Mars. Scientists have posited this chance because the Nineteen Seventies, when the elusive options had been first found by NASA’s Viking lander. This previous May, a earlier paper coauthored by Bickel, bluntly titled “Streaks on martian slopes are dry,” noted that the streaks might play “a major role in the martian dust cycle.”

While proof throws chilly water on options as soon as related to habitability on a dry planet, NASA’s Perseverance Mars rover has not too long ago run into other findings that may level to earlier life on the Red Planet.

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Lead picture: ESA/TGO/CaSSIS

• Molly Glick

  Posted on November 7, 2025

  Molly Glick is the publication editor of Nautilus.