Viking 1 observes a dust storm and Phobos’ shadow

On September 28, 1977, Viking Orbiter 1 observed a dust storm over the site where it had dropped its lander, a little more than a year previously. As Viking 1 orbiter watched, the shadow of Mars' inner moon Phobos passed over the cloud tops. The sequence of images has been artificially colorized and is displayed at a speed ten times that of real time. (Viking images f467a31—f467a69)