Scientists have revealed new details about the far side of the moon, shedding light on its early history.
Also known as the dark side of the moon, the far side of Earth’s natural satellite has long been a source of fascination. The first humans to see the far side of the moon were the crew of Apollo 8. During a series of historic lunar orbits, NASA astronauts Frank Borman, Jim Lovell and Bill Anders became the first to see the side of the Moon that faces away from Earth.
However, certain aspects of the moon’s far side have long been something of a mystery to scientists.
In new research, an international team of scientists provides an explanation for the “strange asymmetry” of the dark side of the moon, which has a different composition to the near side facing Earth.
“The Earth‐Moon system’s history remains mysterious,” they explained in a statement. “Scientists believe the two formed when a Mars‐sized body collided with the proto‐Earth.”
Experts from the Earth-Life Science Institute (ELSI) at Tokyo Institute of Technology, the University of Florida, the Carnegie Institution for Science, Towson University, NASA Johnson Space Center and the University of New Mexico participated in the study, which is published in the journal Nature Geoscience.
An image of the far side of the moon captured by NASA’s Lunar Reconnaissance Orbiter.
When the first images of the far side of the moon emerged decades ago, scientists realized that it has almost no “maria,” or dark regions (from the Latin for sea). Only 1 percent of the far side was covered with maria compared to about 31 percent of the near side, researchers explained.
The new research suggests that this is because radioactive elements were “distributed uniquely” after the collision that formed the moon.
The near side of the Moon, as seen by the cameras aboard NASA’s Lunar Reconnaissance Orbiter spacecraft. (NASA/GSFC/Arizona State University)
“Because of the relative lack of erosion processes, the Moon’s surface records geological events from the Solar System’s early history,” ELSI co‐author Matthieu Laneuville said in the statement. “In particular, regions on the Moon’s near side have concentrations of radioactive elements like U [uranium] and Th [Thorium] unlike anywhere else on the Moon. Understanding the origin of these local U and Th enrichments can help explain the early stages of the Moon’s formation and, as a consequence, conditions on the early Earth.”
The composition of the Moon’s near side is oddly different from that of its far side, and scientists think they finally understand why. (NASA/NOAA)
Last year, China became the first country to successfully land a spacecraft on the far side of the moon.
Distribution of thorium on the lunar surface from the Lunar Prospector mission. Thorium is highly correlated with other radioactive elements (heat producing), with most of it being present on the Earth-facing side (near side). (Laneuville, M. et al (2013) Journal of Geophysical Research: Planets.)
The far side of the moon. The Lunar Reconnaissance Orbiter Camera (LROC ) Wide Angle Camera (WAC) orthographic projection centered at 180° longitude, 0° latitude.
(Credit: NASA/Goddard/Arizona State University)
After Apollo 11, astronauts Neil Armstrong and Buzz Aldrin set foot on the moon on July 20, 1969, only 10 more men — all Americans — walked on the lunar surface. The last NASA astronaut to set foot on the moon was Apollo 17 Mission Cmdr. Gene Cernan on Dec. 14, 1972.
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