'Dark side of the moon' mystery solved after 55 years

Wednesday, June 11, 2014, 6:31 PM - The lunar patterns commonly referred to as the 'Man on the Moon' were formed when meteoroids struck the Earth-facing side of the Moon, creating flat seas of basalt. From Earth, the seas -- which are referred to as maria -- look darker than the rest of the landscape.

But no 'face' exists on the far side and scientists have been unable to determine why. 

There's still a lot to learn about the 'dark' side of the moon, which earned its name because it is an unknown portion of the lunar landscape -- not because sunlight doesn't reach it.

The mystery surrounding the lack of a maria on the far side dates back to 1959, when the first images of that portion of the Moon were captured.

On Monday, scientists from Penn State University announced they may have solved the 55 -year-old conundrum, which is called the lunar far side highlands problem.

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It turns out the lack of a maria has to do with the crust of the moon, which appears to be thicker on the far side.

This can be traced back to the Moon's early formation.

Scientists believe that our Earth and Moon came to be when an object the size of Mars hit our planet's ancestor, causing a massive impact. A chunk of the planet's outer layers were flung into space where it would eventually became the Moon.

Researchers say that shortly after the impact, the Earth and the Moon were hot. They eventually cooled, but at different rates.

The near side took longer to cool because it was exposed to heat radiation from the Earth. The far side, on the other had, cooled quickly -- enabling it to develop a thick crust, protecting it from the effects of the lunar magma that created the maria.

The complete paper can be found in Astrophysical Journal Letters.

The near side of the moon, featuring a prominent basal sea, or maria.