Our familiar near side looks darker in some places – the result of vast ancient lava flows, called the lunar mare – while the far side is covered in craters and craters but no mare.
Astronomers have long puzzled over why the two sides of the moon are so different. However, a study published last week in the journal Science Advances has come up with a new explanation for this lunar mystery.
The researchers found that the impact that formed the trough would have created an enormous plume of heat that would spread inside the moon, according to the statement. This plume would have carried some of the material to the near side of the moon, feeding the volcanoes that created the volcanic plains.
“The question is how this heat affects the internal dynamics of the Moon. What we show is that under any reasonable conditions at the time of SPA formation, it ends up concentrating these heat-producing elements on the near side.
“We speculate that this contributed to the mantle melting that led to the pyroclastic flows we see at the surface.”
The volcanic plains on the near side of the moon are home to a group of Elements including potassium, rare earth elements and phosphorous among others – they are known as Procellarum KREEP terrane (PKT) and are rare elsewhere on the Moon.
The researchers ran computer simulations of how heat from a giant impact changes heat transfer patterns in the moon’s interior, and how this might redistribute KREEP in the lunar mantle.
According to their model, KREEP would have traversed the heat wave emitted from the area of impact “like a surfer” whether the impact was a direct hit or simply wounding the moon. As the heat plume spread under the moon’s crust, this material was eventually transferred to the near side.
“How the PKT formed is the single most important open question in lunar science,” Jones said in the press release.
“And the South Pole-Aitken effect 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.”