Two researchers explained in an article published on The Conversation portal about the origin of the dichotomous structure of the northern and southern hemispheres of Mars.
The so-called ‘Martian hemispheric dichotomy’ is perhaps the greatest mystery of the solar system. This phenomenon has baffled the scientific community since it was discovered from images sent to Earth by the Mariner 9 and Viking probes in the early 1970s.
The photographs showed significant differences in the elevation of the terrain of the highlands (southern hemisphere) and the lowlands (northern hemisphere). Subsequently, contrasts were detected in the thickness of the crust between both hemispheres, as well as in the density of impact craters and the intensity of the magnetic field.
The origins of this dichotomy have been the subject of debate, with several hypotheses proposed. Scientists don’t agree whether it was formed by external factors, such as the collision of a huge Moon-sized asteroid, or by internal factors, such as the flow of heat through the interior of Mars.
Unraveled the mystery
In a new study recently published in the journal Geophysical Research Letters, Hrvoje Tkalcic and Sun Weijia, professors at the Australian National University and the China Institute of Geology and Geophysics, respectively, determined that the Martian dichotomy originated deep inside the planet. red. Scientists arrived at this result by probing the interior of Mars using marsquake data recorded by the seismometer aboard NASA’s Insight lander, located near the boundary separating the two sides of the dichotomy.
According to the authors of the research, a group of new marsquakes was found in the Terra Cimmeria region, in the southern highlands, in addition to a group of 16 previously identified marsquakes in Cerberus Fossae, in the northern lowlands.
They also observed that the seismic wave attenuation quality factor of the Terra Cimmeria marsquake array was lower than that of the Cerberus Fossae array. This seismic attenuation disparity could be attributed to temperature variations between the two hemispheres, as well as more vigorous convection beneath the surface of the southern highlands.
This latter phenomenon is due to the thicker crust in the southern hemisphere slowing down heat loss from inside the mantle, making it more fluid. The specialists concluded that mantle convection is the main cause of the dichotomy on the surface of Mars. These findings support the hypothesis that the Martian dichotomy was caused by internal factors and not by the impact of a celestial body. With RT
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