In June 2018, a dust storm formed near Mars Exploration Rover (MER) Opportunity. In the early days of the storm, scientists belived the dust storm would not significantly impact the rover. However, over the next serveral days the storm intensified into a "planet encircling" storm that blocked out the sun.
This image shows what the sun looked like through the dust storm surrounding Opportunity. As the storm intensified it blocked nearly all light from reaching the surface of the planet, plunging Opportunity into perpetual darkness.
