(ORDO NEWS) — For several decades now, scientists have been puzzled by one feature of the Red Planet: Mars seems to have two faces. The relief of its northern hemisphere is represented by flat lowlands, while the southern one is cut up by highlands and pitted with canyons. What is the reason for this “duplicity”?
According to the difference between the hemispheres, Mars became the champion among the planets of our solar system. Despite the fact that today there are many theories and versions that explain the differences in the relief of the two hemispheres, there are still very few specific answers.
Geophysicists at ETH Zurich, led by Giovanni Leone, have recently put forward a new explanation for this phenomenon. Leone is the lead author of a paper that was recently published in Geophysical Research Letters.
Thanks to a computer model, scientists came to the conclusion that a large celestial object could crash into the Red Planet from the South Pole. It is assumed that the collision occurred in the early period of the history of the solar system.
The model that scientists have created shows that magma could have spilled into the Southern Hemisphere as a result of the explosion. At the same time, the mass of the celestial body that collided with Mars should have been at least one tenth of the mass of the Red Planet.
Only in this case could the energy sufficient for the formation of such an amount of magma be released. According to this version, the molten rock eventually solidified, and numerous highlands formed in the southern hemisphere of Mars.
Creating a model, scientists suggested that the celestial body consisted largely of iron, its radius reached at least 1600 kilometers, and it crashed into Mars at a speed of five kilometers per second. According to researchers, this collision occurred from 4 to 15 million years after the formation of the Red Planet.
At that time, the crust of Mars was probably very thin, like icing on creme brulee, and under the crust, like under the icing of a popular dessert, there was a liquid substance – molten magma.
When a celestial object collided with Mars, it increased the mass of the planet, in particular due to iron. However, the model also showed that the impact caused intense volcanic activity that lasted for three billion years. The collision led, among other things, to numerous magmatic emissions around the equator. Over time, this magma migrated to the South Pole, where it solidified.
The researchers also found that volcanic activity on Mars ceased after about three billion years. This does not contradict the available data obtained in the course of observations and measurements.
Theories put forward earlier argued otherwise. According to them, the space object was supposed to collide with Mars from the side not of the Southern, but of the Northern Hemisphere.
The most significant theory explaining the dichotomy of Mars was put forward by two American researchers in 1984. It was published in the journal Nature. According to this theory, a large celestial object collided with the North Pole of Mars.
However, Leone refutes this theory. The highlands of volcanic origin on Mars are not unevenly distributed: they dominate in the Southern Hemisphere and, with the exception of a few, are absent in the Northern Hemisphere. According to the scientist, it is the new model that corresponds to reality.
The scientist explains that if you choose the composition and size of a celestial body that collided with Mars, the model almost accurately reproduces the relief of the hemispheres.
However, in this case, the celestial body should have consisted of 80% iron. When the researchers simulated a collision with a celestial body made of silicate rock, the result did not correspond to reality.
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