Sol 4106, August 13, 2015. Late afternoon sunlight (3:55 pm local time) casts the rover’s shadow eastward and also creates a “hot spot” on the ground. This, on a local scale, is the same opposition effect that makes a Full Moon appear so bright from Earth. Every bit of ground in the down-sun direction is fully lit, with no shadow visible. The image is a composite of two Navcam frames; click to enlarge.
Opportunity raw images, its latest mission status, a location map. and atmospheric opacity, known as tau.