They call it Hellas Planitia, and to our best knowledge, it occupies a place in the top five largest impact craters in the Solar System. It’s also home to “an enigmatic formation” called banded terrain, to use the phrasing of the scientists studying the planet. Hellas Planitia is considered Mars’ largest unambiguous impact structure, measuring 1,400 miles (2,253 km) in diameter and up to 9,800 feet (3 km) deep, “the lowest elevations on Mars.” It’s believed to be the result of an impact with a huge piece of floating rock that occurred some 4 billion years ago. Being such an important feature of the planet, Hellas Planitia has been an object of study for human scientists for years now. The HiRISE camera that’s orbiting the planet has snapped instances of it several times already, revealing more and more of the location’s mysteries. The image we have here was captured by HiRISE in March this year, from an altitude of 255 km (158 miles). It shows an area that is just 1 km (0.62 miles) across, but most importantly the said “enigmatic formation called banded terrain.” According to the people over at NASA and the University of Arizona, who are studying these images, this type of formation can only be found in the northwest of the Hellas basin. It’s located in the deepest part of the basin, and comes to light as “smooth bands of material separated by ridges or troughs, with circular and lobe shapes that are typically several kilometers long and a few hundred meters wide.” In some areas, the terrain seems to have undergone deformation, but scientists do not know what was the cause of that. “There are several ideas for what it could be, including a thin, flowing, ice-rich layer or sediment that was deformed beneath a former ice sheet,” they say. So, until we get a better understanding of how these features came to be and what they represent, let’s add banded terrain to the growing list of Martian wonders we don’t fully comprehend at the moment.