The closest side we’re so familiar with appears darker in places—the result of the huge ancient lava flows called moon mare—while the other side is covered in pockmarks and craters, but no mare.
Why the two sides of the moon are so different has long puzzled space scientists. However, a study published last week in the journal Science Advances has found a new explanation for this lunar mystery.
The researchers found that the impact that formed the basin would have created a huge heat plume that spread the moon’s interior, according to the statement. That plume would have carried certain materials to the near side of the moon, fueling the volcanism that created the volcanic plains.
“The question is how that heat affects the moon’s internal dynamics. What we’re showing is that under all plausible conditions at the time SPA formed, it ends up concentrating these heat-producing elements on the near side.
“We expect this contributed to the melting of the mantle that produced the lava flows we see on the surface.”
The volcanic plains on the nearest side of the moon are home to a group elements like potassium, rare earth elements, phosphorus and others — known as Procellarum KREEP terrane (PKT) which is rare elsewhere on the moon.
The researchers ran computer simulations of how heat generated by a giant impact would alter heat transfer patterns in the moon’s interior, and how that could redistribute KREEP material in the moon’s mantle.
According to their model, the KREEP material would have ridden the heat wave emanating from the impact zone “like a surfer,” whether the impact was a direct hit or simply grazed the moon. As the heat plume spread beneath the moon’s crust, that material was eventually delivered to the near side.
“How the PKT formed is perhaps the most important open question in lunar science,” Jones said in the press release.
“And the impact on the South Pole-Aitken is one of the most important events in the history of the moon. This work brings those two things together and I think our results are really exciting.”
