The bifurcation between the far and near side of the Moon
Through simulations and models, astronomers have concluded that, unlike the far side, the near side of the Moon is covered by what is called the Lunar Mary. These are basically huge volcanic basalt plains that appear as dark spots on the lunar surface when viewed from Earth. The models even supported the theory that a huge impact on the lunar surface reappeared on the nearby side in lava flows, thus reflecting different geological compositions on both sides. Apart from this, existing theories also suggest that a sea of magma once covered the nearby side, however, what caused this volcanic activity is still disputed. When this side cooled, it made the rocky surface in a smooth landscape and created dark imperfections visible to this day. According to a study published in Science Advances, a huge crater called the South Pole – Aitken Basin (SPA) at the lunar south pole may have the answer. Experts have discovered that the basin was created by one of the largest and oldest conflicts about 4.3 billion years ago. In addition, scientists believe that the collision generated such heat that it warmed the upper mantle nearby and led to the accumulation of heat-producing elements such as thorium, potassium, rare earth elements and phosphorus. Surprisingly, these elements have also been found in rock samples transported to Earth under NASA’s Apollo program. According to Science Alert, planetary scientist Matt Jones from Brown University said, “What we are showing is that under any reasonable circumstances at the time the SPA was formed, it ends up collecting these elements that produce heat nearby.” “We expect this to have contributed to the melting of the mantle that produced the lava flows we see on the surface,” he added. Finally, the scientists concluded that the difference in the two lunar surfaces was due to two reasons. The first is the upper mantle in the southern hemisphere which heats up and flows to the northern hemisphere and the second is the upper mantle on the far side which remains too cool to distribute the mantle similarly. “And the South Pole-Aitken collision is one of the most important events in lunar history. This project brings these two things together and I think our results are really exciting,” Jones said.
