"The surface of the Earth is the shore of the cosmic ocean... Recently, we've managed to wade a little way out, and the water seems inviting." - Carl Sagan
Mysterious white rock fingers on Mars
What caused this unusual white rock formation on Mars? Intrigued by the possibility that they could be salt deposits left over as an ancient lakebed dried-up, detailed studies of these fingers now indicate that this is not correct. The light material appears to have eroded away from the surrounding area, indicating a very low-density composition, possibly consistent with volcanic ash or windblown dust. The stark contrast between the rocks and the surrounding sand is compounded by the sand’s unusual darkness. This picture was taken from the Mars Express spacecraft currently orbiting Mars. The mysterious white rock spans about 15 kilometers across inside a larger crater that spans about 100 kilometers.
Image credit: G. Neukum (FU Berlin) et al., Mars Express, DLR Mars Express