THEMIS Image of the Day, March 15, 2019. This VIS image is located on the South Polar cap. The linear features are the steep side of a polar trough. At troughs the extensive layering of the ice is exposed. The layers represent deposition of ice and dust during changing seasons over millions of years.
In the upper half of the image is a faint circular feature. It most likely shows where the rim of an impact crater lies buried under a shallow layer of ice.