An international team of astronomers led by researchers from Tokyo Institute of technology has conducted a series of experiments, the results of which helped to give a new explanation for the strange asymmetry of the moon. Scientists believe that the parties to this satellite differ from each other because of the content of radioactive elements.
A study published in the journal Nature Geoscience, and briefly about it tells EurekAlert. As you know, the Moon is "near side", which is constantly turned towards the Earth, and "far side" which is always facing away from Earth. That is from our planet it is possible to observe only one side.
However, until the middle of last century, astronomers believed that the two sides of the moon are the same. And only use space probes helped determine what side of the satellite differ significantly from each other at the surface. This can be seen even visually.
On "close" side of the moon even with the naked eye can see light and dark spots. Early astronomers called these dark areas "maria" which translated from Latin means "sea". Scientists believed that this water, like the earth.
More than a century ago, the use of telescopes has allowed to establish that the "sea" are in fact craters. In our time, it was estimated that "far" side of the moon "sea" cover only about one percent of the surface, while on "close" side – about 31 percent.
The cause of this asymmetry for a long time to install failed. Helped analyze samples of lunar soil. Scientists have found that the relative "dark spots" associated with their geological composition, which, in fact, is associated with the volcanism. It was also determined the signature of this breed, which received nazvanie KREEP (this is a reduction, which means rocks, rich in potassium, REE – rare Earth elements such as cerium, dysprosium, erbium, europium, and others, and P – phosphorus).
Potassium, thorium and uranium are radioactive unstable elements. This means that they are found in a variety of atomic configurations which have a variable number of neutrons. These atoms are of variable composition known as "isotopes". Some of them are unstable and decay to form other elements and releasing heat.
Conducted scientific tests have proven that in the conditions of the moon heat from the radioactive decay of these elements could melt the rocks in which they are contained. This, in turn, explains their joint localization. The study also showed that the presence of KREEP component in the rock lowers its melting point.
The work proves that the moon was attended by active volcanic activity. Craters appeared where there was a high concentration of radioactive elements, have on "close" side.
The researchers believe that their discovery will help better understand the mechanism and the chronology of the evolution of the moon. Generally accepted theory that it was formed as a result of the Earth’s collision with a cosmic object called Thea.
