The aureole of the highest volcano in the solar system
Shortly after the discovery of the giant shield volcano Olympus Mons on the Red Planet by the U.S. space probe Mariner 9 in 1971, planetary scientists had noticed that the volcano was surrounded by an aureole of very characteristic terrain. It extends over hundreds of kilometers into the surrounding area. The aureole tells the story of the catastrophic collapse of the lower flanks of Olympus Mons that occurred in its distant past.