Sand Sheet on Crater Floor (Released 12 April 2005)

One of the topics of Image of the Day was dunes, and examined the north polar sand sea and isolated dune fields at lower latitudes. Sand seas on Earth are often called "ergs", an Arabic name for dune field. A sand sea differs from a dune field in two ways: 1) a sand sea has a large regional extent, and 2) the individual dunes are large in size and complex in form. As with yesterday's image, this dune field is located inside a crater. In this VIS image the dunes are coalescing into a sand sheet. Note the lack of dune forms to the north of the small hills. The presence of ridges and hills in the area is affecting the dune shapes.