Images taken by NASA's Curiosity Mars rover on April 2 and
April 3 include bright spots, which might be due to the sun glinting off a rock
or cosmic rays striking the camera's detector.
The image from April 3, from Curiosity's Navigation Camera,
is online at: http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA18077
The rover took the image just after arriving at a waypoint
called "the Kimberley." The bright spot appears on a horizon, in the
same west-northwest direction from the rover as the afternoon sun.