The moon always shows us the same facea family face full of dark “seas” of basalt. But what about his hidden face? For decades, we have known what is radically different: More mountainous, with a thicker and firing cortex of craters, but with much less volcanic activity. This enigma, of having a moon with two faces, has been one of the great mysteries of astronomy. Now We are getting to know More details of its composition.
As. The key lies in the first rock samples brought from the hidden face of our satellite by Chinese mission chang’e-6 that has given us the key to continue investigating in this line. That is why a research team from the University of Peking and College London University He has discovered that the interior of the hidden face of the moon is significantly colder than that of the visible face. And this temperature difference is key to everything.
The analysis. When starting to study the fragments extracted from the Aitken basinscientists have confirmed the first of all the age of the stones. Specifically, they have seen that these rocks were formed from Lava about 2.8 billion years ago. But the real surprise came to see the chemical “thermometer” of its minerals.
The results, published in the prestigious magazine Nature GeoscienceThey show that this lava was formed at a temperature of about 1,100 ° C. That said, it may not seem much, but it is approximately 100 ° C longer than the lavas that gave rise to the seas of the visible face, according to the samples brought by the missions Apollo and Chang’e-5.
“The visible face and hidden face of the moon are very different on the surface and, potentially, inside. It is one of the great mysteries of the Moon. We call it the two -sided moon,” explains Professor Yang Li, co -author of the study.
Testing. Faced with evidence like this, the only thing that can be done is to be sure of what is being said, and for this the scientific team arrived a second method of analysis. In this case, the satellite remote sensing data of the Chang’e-6 landing zone with a similar age region on the visible face were compared. The result was consistent: the potential temperature of the mantle of the hidden face was about 70 ° C lower. In this way, there was no doubt: the interior of the hidden face was colder.
Because. The answer seems in this case a “cocktail” of chemical elements that has been called from Kreep. This acrononic groups Potassium (K), Phosphorus (P) and Rare Earth (REE), which in turn is also accompanied by radioactive elements such as uranium and thorium.
The key to all this, which is the elements act as an internal “thermal blanket.” As they disintegrate radioactively, they generate heat, maintaining the hottest mantle for longer and favoring volcanic activity. But the truly interesting thing is that the Kreep distribution is not uniform, but is almost everything concentrated in the visible face of the satellite.
This is something that Chang’e-6 samples confirm Retrieved: the basalts of the hidden face have a less or insignificant Kreep component ‘. Without that extra heat source, its mantle cooled faster, the bark became thicker and, therefore, volcanism was much more scarce.
The final mystery. This matter does not stay here, since more questions are raised in this regard, such as why all the Kreep material ended in the visible face? This question is not answered by this study, but confirms the real thermal asymmetry of the moon, giving more weight to several fascinating theories. Among them is one of the most accepted hypotheses that points to the gigantic impact that formed the Aitken basin in the hidden face (the largest crater of the solar system). In this case we talk about being so violent, the impact pushed the magma rich in Kreep to the opposite side, the visible face.
Another theory suggests that the Earth initially had two moons. The smallest ended up slowly colliding with the largest, forming the thickest bark of the hidden face and explaining the composition difference that has now been demonstrated. But in the end we are talking about hypotheses that must still be confirmed in subsequent studies.
Images | POT Chuttersnap
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