Scientists provide new explanation for the strange asymmetry of the moon

[flash13]

Scientists provide new explanation for the strange asymmetry of the moon

The composition of the Moon's near side is oddly different from that of its far side, and scientists think they finally understand why. Credit: NASA/NOAA

 

The Earth‐moon system's history remains mysterious. Scientists believe the system formed when a Mars‐sized body collided with the proto‐Earth. Earth ended up being the

 

larger daughter of this collision and retained enough heat to become tectonically active. The moon, being smaller, likely cooled down faster and geologically froze. The apparent

 

early dynamism of the moon challenges this idea.

 

New data suggests this is because radioactive elements were distributed uniquely after the catastrophic moon‐forming collision. Earth's moon, together with the sun, is a

 

dominant object in the sky and offers many observable features providing evidence about how the planet and the solar system formed. Most planets in the solar system have

 

satellites. For example, Mars has two moons, Jupiter has 79 and Neptune has 14. Some moons are icy, some are rocky, some are still geologically active and some relatively

 

inactive. How planets got their satellites and why they have the properties they do are questions that could shed light on many aspects of the evolution of the early solar system.

 

The moon is a relatively cold rocky body with a limited amount of water and little tectonic processing. Scientists presently believe the Earth‐moon system formed when a Mars‐

 

sized body dubbed Theia—who in Greek mythology was the mother of Selene, the goddess of the moon—catastrophically collided with the proto‐Earth, causing the components

 

of both bodies to mix.

 

The debris of this collision is thought to have rapidly separated to form the Earth and moon, perhaps over a few million years. The Earth ended up being larger, and its size was

 

just right for it to become a dynamic planet with an atmosphere and oceans. Earth's moon ended up being smaller and did not have sufficient mass to host these characteristics.

 

Thus, thanks to the dynamics of the collision that formed the Earth-moon system, Earth exhibits idiosyncrasies such as retaining volatile substances like water or the gasses that

 

form the atmosphere, and having sufficient internal heat to maintain long‐term planetary volcanism and tectonics. Decades of observations have demonstrated that lunar

 

history was much more dynamic than expected, with volcanic and magnetic activity occurring as recently as 1 billion years ago, much later than expected.

 

Back then, most scientists assumed the far side of the moon, which they would never have been able to see, was more or less like the near side.

 

However, because the moon is relatively close to the Earth, only about 380,000 km away, the moon was the first solar system body humans were able to explore, first using non‐

 

crewed spacecraft and then manned missions. In the late 1950s and early 1960s, non‐crewed space probes launched by the USSR returned the first images of the far side of the

 

moon, and scientists were surprised to find that the two sides were very different. The far side had almost no maria. Only 1% of the far side was covered with maria compared

 

with ~31% for the near side. Scientists were puzzled, but they suspected this asymmetry offered clues as to how the moon formed.

 

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). The relationship between this region and many observed features of lunar history is a key question in lunar sciences. Credit:

 

Laneuville, M. et al (2013) Journal of Geophysical Research: Planets.

 

In the late 1960s and early 1970s, NASA's Apollo missions landed six spacecraft on the moon, and astronauts brought back 382 kg of moon rocks to try to understand the origin

 

of the moon using chemical analysis. Having samples in hand, scientists quickly figured out the relative darkness of these patches was due to their geological composition, and

 

they were, in fact, attributable to volcanism. They also identified a new type of rock signature they named KREEP—short for rock enriched in potassium (chemical symbol K), rare‐

 

earth elements (REE, which include cerium, dysprosium, erbium, europium, and other elements which are rare on Earth) and phosphorus (chemical symbol P), which was

 

associated with the maria. But why volcanism and this KREEP signature should be distributed so unevenly between the near and far sides of the moon presented a puzzle.

 

Now, using a combination of observation, laboratory experiments and computer modeling, scientists from the Earth‐Life Science Institute 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 have uncovered new clues regarding

 

how the moon gained its near‐ and far‐side asymmetry. These clues are linked to an important property of KREEP.

 

Potassium (K), thorium (Th) and uranium (U) are radioactively unstable elements. This means that they occur in a variety of atomic configurations that have variable numbers of

 

neutrons. These variable composition atoms are known as isotopes, some of which are unstable and fall apart to yield other elements, producing heat.

 

The heat from the radioactive decay of these elements can melt the rocks they are contained in, which may partly explain their co‐localisation.

 

This study shows that, in addition to enhanced heating, the inclusion of a KREEP component to rocks also lowers their melting temperature, compounding the expected volcanic

 

activity from simply radiogenic decay models. Because most of these lava flows were emplaced early in lunar history, this study also adds constraints about the timing of the

 

moon's evolution and the order in which various processes occurred on the moon.

 

This work required collaboration among scientists working on theory and experiment. After conducting high-temperature melting experiments of rocks with various KREEP

 

components, the team analyzed the implications this would have on the timing and volume of volcanic activity at the lunar surface, providing important insight about the early

 

stages of evolution of the Earth‐moon system.

 

ELSI co‐author Matthieu Laneuville says, "Because of the relative lack of erosion processes, the moon's surface records geological events from the solar system's early history. In

 

particular, regions on the moon's near side have concentrations of radioactive elements like U and Th 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 results from this study suggest that the moon's KREEP‐enriched maria have influenced lunar evolution since the moon formed. Laneuville thinks evidence for these kinds of

 

non‐symmetric, self‐amplifying processes might be found in other moons in our solar system, and may be ubiquitous on rocky bodies throughout the universe.

 

A clue as to why the near and far side of the moon are so different comes from strong asymmetry observable in its surface features. On the moon's perpetually Earth‐facing near

 

side, dark and light patches are observable with the naked eye. Early astronomers named these dark regions 'maria," Latin for 'seas," thinking they were bodies of water by

 

analogy with the Earth. Using telescopes, scientists were able to figure out over a century ago that these were not in fact seas, but more likely craters or volcanic features.

 

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[flash13]

Why is the far side of the moon so weird? Scientists may have solved a lunar mystery

New study aims to understand the moon's asymmetry.

 

In a new study, scientists explore a new theory that aims to explain why the moon's near and far sides are so different.

 

(Image: © NASA/NOAA)

 

The moon's mysterious far side is so much different than its near side, which we see in the night sky, and now scientists think they know why.

 

The moons near side and far side were once thought to be relatively similar. But, with missions by robotic observers and Apollo astronauts in over the last six decades, scientists have found that

 

they have significantly different features, many related to the moon's geologic activity. In fact, observations have shown that only about 1% of the moon's far side is covered with maria, or craters

 

caused by volcanic activity on the moon. This sharply contrasts the object's near side, 31% of which is covered with maria.

 

According to the giant-impact hypothesis, about 4.5 billion years ago the Earth and the moon formed when a Mars-sized object smashed into the proto-Earth. Earlier theories suggested that the

 

moon, because it was a smaller object, cooled down faster than the Earth after this impact and geologically "froze." But the idea that the moon "froze" after this event is an idea that has been

 

challenged as studies have shown evidence of relatively recent geologic activity on the moon, with evidence of volcanic and magnetic activity on the moon occurring as recently as 1 billion years

 

ago.

 

n the new study, researchers from the Earth‐Life Science Institute 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 investigated the moon's geologic history and found a new explanation for the asymmetry between its far and near sides.

 

Through a number of experiments, computer modeling and the use of existing observations of the lunar surface, these researchers found that concentrations of radioactive elements on the moon

 

could help to explain the asymmetry between the near and far sides of the moon.

 

This study showed that radioactively unstable elements including Potassium (K), thorium (Th) and uranium (U) create heat through the process of radioactive decay. This heat can melt the rocks

 

where these elements are located.

 

"Because of the relative lack of erosion processes, the moon's surface records geological events from the solar system's early history. In particular, regions on the moon's near side have

 

concentrations of radioactive elements like U and Th 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," co-author Matthiew Laneuville, a planetary scientist at the Earth Life Science Institute, said in a statement.

 

Additionally, researchers found, the asymmetry is also linked to a property of KREEP, a rock signature which is short for potassium (chemical symbol K) enriched rock, rare‐earth elements (REE —

 

which includes cerium, dysprosium, erbium, europium, among others) and phosphorus (chemical symbol P), which is associated with lunar maria. KREEP was first identified with NASA's crewed

 

Apollo missions to the lunar surface and is associated with maria and therefore volcanic and other geologic activity.

 

According to this study, in addition to heating caused by radioactive decay from unstable elements, KREEP-enriched material on the lunar surface has lower melting points. This only added to

 

expected geologic changes.

 

The combined results of this study suggest that KREEP-enriched maria have been changing the lunar landscape since the rocky satellite was first formed billions of years ago.

 

 

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[PLASMA]

Take a look at the far dark side of the moon, that is why is always👇

             hidden.

 

 

[Karlston]

Similar topics merged.