Colossal Ancient Impact on the Moon's South Pole May Explain Differences Between Lunar's Near and Far Side

The Moon's near-side is known to look different than the pockmarked far side that is not visible from Earth. The nearside is dominated by vast, dark-colored remnants of lava, while the far side of the on is virtually devoid of such marks. It is one of the mysteries of the Moon that scientists have sought to answer.

As to why these two sides have different composition and appearance, scientists from Brown University believes it relates to a massive impact that happened 4.3 billion years ago near the Moon's south pole.

Differences Between the Moon's Near and Far Side

The lunar missions in the 1960s by the Soviet and US Apollo left a historical mark in studying the lunar surface. Through these missions, scientists learned that the near and far sides of the Moon are different from each other in terms of composition and appearance.

Differences in volcanic deposits are plain to see, but their geochemical composition was once unknown. MailOnline reported that the nearside of the Moon is home to a compositional anomaly called the Procellarum KREEP terrane (PKT), which is composed of a concentration of potassium (K), rare earth elements (REE), phosphorus (P), and thorium.

From the years of research on the lunar surface, scientists found that KREEP is concentrated in and around the largest of the nearside volcanic plains, called Oceanus Procellarum. However, it is also sparse in most areas of the Moon.

Scientists suspect a connection between PKT and the lava flows on the nearside. They also questioned why the elements were only concentrated on the Moon's nearside.

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Massive Lunar Impact Influenced Differences of Moon's Near and Far Side

In the study titled "A South Pole-Aitken Impact Origin of the Lunar Compositional Asymmetry," published in Science Advances, researchers showed that the impact that formed the giant South Pole-Aitken basin (SPA) of the Moon about 4.3 billion years ago would have created a massive plume of heat that went through the Moon's interior and carried the KREEP to the nearside.

According to Science Daily, scientists proposed that these elements must have contributed to the volcanism that created the volcanic plains to that side.

Study lead author Matt Jones, a Ph.D. candidate at Brown University, said their study aims to answer how the heat from the ancient lunar impact affected the Moon's internal dynamics. They believe that this contributed to the melting of the Moon's mantle that produced lava flows on the lunar surface.

The team conducted simulations of how heat from the giant impact would alter convection patterns on the Moon's interior and how KREEP might be distributed on the lunar mantle. Lunar interior models suggest that it should be evenly distributed beneath the lunar surface. However, the model they created showed that the impact of the SPA would have disrupted the heat plume.

The research provides a credible explanation as to why the two sides are different, giving an end to one of Moon's mysteries.

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