In yet another cool image from the HiRISE camera on the Mars Reconnaissance Orbiter near Mars, we see these dunes on the planet's surface. This image comes from the Hellespontus region of Mars, where sand from local mesas has been molded into these shapes by high intensity winds. No word yet on whether the famous canals of Mars are actually wormsign. You can learn more about Martian sand dunes here. Photo via AP, HO, and NASA.