martian gullies

NASA today announced the discovery of what appear to be signs of water recently flowing on the surface of Mars. In new photos of large Martian gullies taken by the Mars Global Surveyor not long before it expired, scientists noticed several instances of light-colored streaks that had not appeared in past photos of the same regions taken as recently as 2001. The light coloring is especially exciting considering that meteor impacts and Mars rovers tend to leave dark trails in the soil.