These Martian "kidney beans" aren't safe to eat: they're actually frozen sand dunes in Mars' northern hemisphere爱上海419. A recently released photo by NASA's Mars Reconnaissance Orbiter (MRO) shows a top-down view of the frosty legume lookalikes, taken to help scientists determine if conditions on the Red Planet could have sustained life a long time ago.上海花千坊

In the photo, taken in Sept. 2022 and publicly released in Dec. 2024, the dunes appear surprisingly motionless. Dunes on both Mars and Earth usually migrate as wind picks up grains of sand from one side of a dune and drops them off at another, making deserts look like slow-motion seas. However, the dunes in the photo are covered in a layer of carbon dioxide frost during the northern hemisphere winter on Mars. The frost stops wind from scooping up sand, preventing the dunes from migrating until the spring thaw comes.

Pictures of frost-covered dunes help scientists learn whether water ever existed on the planet's surface for long enough for life to evolve and survive on Mars Even though the frost is made from carbon dioxide, not water, it still influences the odds that Mars had water for long periods in the past.

Related: Hundreds of black 'spiders' spotted in mysterious 'Inca City' on Mars in new satellite photos上海新茶工作室微信

The amount of carbon dioxide on Mars varies depending on how the planet is angled relative to the sun. Earth wobbles just a bit as it spins on a slightly-tilted axis, and this gives us different seasons. But Mars' axial tilt wobbles a lot over the course of millions of years, drastically changing its seasons. When Mars is tilted far enough, carbon dioxide ice turns into gas on a large scale — enough to give the whole planet a thicker atmosphere. This thicker atmosphere might have been enough to support liquid water over long periods.