What's happening on Mars? Images taken decades apart show surface changing

A comparison of images captured decades apart by NASA and the ESA has revealed that a massive dark patch is creeping across the surface of Mars, leaving scientists puzzled. Located in the vast plains of Utopia Planitia in the northern hemisphere of the Red Planet, the dark patch observed in photos is ground covered with volcanic rocks and ash from eruptions that occurred millions of years ago. The feature was first photographed by NASA's Viking probes way back in 1976, and photos captured since then have shown the shadowy feature expanding across the surrounding landscape: the latest images captured by ESA's Mars Express orbiter in 2024 were released on 15 April this year, and showed that the dark patch's southern boundary had expanded by at least 320 kilometers. This suggests that the patch has been expanding at a rate of roughly 6.5 km per year. While scientists are certain that the dark patch in question is the result of volcanic eruptions and that its expansion has something to do with strong winds on Mars, which are known to kick up dust and ash from the surface, they are unsure of what exactly is behind the observed expansion. Currently, there are two hypotheses to explain this phenomenon: either volcanic ash is being picked up and moved around by strong Martian winds, or the ochre-colored dust that previously covered the volcanic ash has been blown away by gusts, leaving the dark patch underneath exposed. However, there is currently no consensus on which hypothesis is correct, as per the ESA. Video Credit: ©ESA