The first structures to grab the attention of scientists were the black stains that emerged from the storm. As the dust settled, these stains continued to expand until they finally revealed their secret: they were gigantic volcanoes, the largest ever seen by man. One of them, Mount Olympus, was more than 17 000 meters high and its diameter at the base measured about 500 kilometers, slightly less than the distance from Milan to Rome. The only structure that it compares with on the Earth is Mauna Loa, the huge volcanic structure that forms the main Hawaiian island and which projects above the water to more than 4 500 meters, but which rises from the bottom of the Pacific ocean for more than 10 000 meters. It was just this analogy that made Mount Olympus even more interesting. In fact, considering the entire formation, it was discovered that it is surrounded by a slope on which it rests on a rather uniform plain. Someone then asked what we would see if the ocean water was removed around Hawaii: the answer is an enormous mountain whose profile is in the higher part, now immersed in the water, with a gentle slope, but then which drops off brusquely and is transformed into a slope eroded by the sea. In reality, the slope of Mount Olympus was probably carved by the wind, a force whose power was directly confirmed. But, while the pictures were received on Earth, just imagine how long the theory was considered that Mars once had vast expanses of clear water for which the slope of Mount Olympus was the living proof! And this was also because the surprises provided by Mariner 9 were long from being over: other structures were about to be revealed and they would have explained another part of the history of Mars.
The first structures to grab the attention of scientists were the black stains that emerged from the storm. As the dust settled, these stains continued to expand until they finally revealed their secret: they were gigantic volcanoes, the largest ever seen by man. One of them, Mount Olympus, was more than 17 000 meters high and its diameter at the base measured about 500 kilometers, slightly less than the distance from Milan to Rome. The only structure that it compares with on the Earth is Mauna Loa, the huge volcanic structure that forms the main Hawaiian island and which projects above the water to more than 4 500 meters, but which rises from the bottom of the Pacific ocean for more than 10 000 meters. It was just this analogy that made Mount Olympus even more interesting. In fact, considering the entire formation, it was discovered that it is surrounded by a slope on which it rests on a rather uniform plain. Someone then asked what we would see if the ocean water was removed around Hawaii: the answer is an enormous mountain whose profile is in the higher part, now immersed in the water, with a gentle slope, but then which drops off brusquely and is transformed into a slope eroded by the sea. In reality, the slope of Mount Olympus was probably carved by the wind, a force whose power was directly confirmed. But, while the pictures were received on Earth, just imagine how long the theory was considered that Mars once had vast expanses of clear water for which the slope of Mount Olympus was the living proof! And this was also because the surprises provided by Mariner 9 were long from being over: other structures were about to be revealed and they would have explained another part of the history of Mars.
