During the festive season, many people look forward to a white Christmas in their local areas. However, the European Space Agency (ESA) has brought a touch of festive spirit with an image of a white Christmas on Mars. This captivating image was captured by ESA's Mars Express spacecraft, which orbits the planet and is equipped with a high-definition camera. The photo was taken by the Mars Express' High Resolution Stereo Camera (HRSC) in the Australe Scopuli region of Mars' southern hemisphere in June 2022 and was only recently released as a celebration.

Discovering the Mysterious Mars

We often think of Mars as the red planet due to the rust-colored dust that covers most of its surface, known as regolith. But there are also large areas covered in ice and snow. Although there is very little liquid water on Mars, there is an abundance of frozen water, especially near the poles. The swirling shapes in the image are the result of layers of snow and ice that have accumulated on the hills in this region.When sunlight shines through the translucent top layers of the carbon dioxide ice, it warms the underlying surface. The ice at the bottom of the layer starts to sublimate, creating pockets of trapped gas. The pressure builds up until the overlying ice suddenly cracks, resulting in a burst of gas jetting through the surface. These gas fountains carry dark dust from below, which falls back to the surface in a fan-shaped pattern shaped by the prevailing wind. The fans can range in length from tens to hundreds of meters. This sublimation process, where material goes directly from solid to gas without passing through the liquid stage, is already happening, as evidenced by the dark patches near the bottom of the image. Here, the ice has sublimated away, revealing the darker material beneath.If you have a pair of 3D glasses, you can explore a stereoscopic version of this image on the ESA's website and gain a more immersive experience of Mars' unique features.The southern hemisphere of Mars is not in winter but is approaching summer. The increasing warmth of the sun is further shaping these ice layers, adding to the planet's fascinating geological phenomena. The ESA's Mars Express mission continues to provide us with valuable insights into the red planet and its ever-changing landscapes.