Tech UPTechnologyEarth had two moons

Earth had two moons

dos-lunasNow our planet has only one satellite, butEarth once had two moons until one of them, the smaller one, crashed into its older sister-25 times heavier- in the lunar mountainous region known as the lunar highlands, according to a new study by scientists at the University of California, Santa Cruz (UCSC), in the US.

The work, published in the magazineNature, is based on the “big shock theory”, according to which an object the size of Mars collided with the Earth in the early history of the Solar System and the ejected elements came together to form the Moon. The study suggests that this gigantic impact also created another, smaller object, which originally shared orbit with the satellite, but fell on Earth around 4.4 billion years ago, long before there was life on Earth, which it was covered on one side by a layer of solid crust kilometers thick.

Thiswould explain why the closest side of the Moon is relatively low and flat, while the topography of its far side is high and mountainous, with a thicker crust. “This study agrees with what is known about the dynamic stability of this system, the cooling process of the Moon, and the ages of the lunar rocks,” says UCSC professor of earth and planetary sciences, Erik Asphaug.

To verify this, Asphaug and his colleagues created computer simulations of an impact between the Moon and a companion three times smaller to study the dynamics of the collision and track the evolution and distribution of lunar material. “In a low-speed collision, the impact does not form a crater and does not cause melting; instead, most colliding materials pile up in the affected hemisphere forming a thick layer of solid crust, creating a mountainous region comparable in extent. with the lunar highlands of the hidden side, “they point out.

The modelcould also explain variations in the composition of the Moon’s crust, which is dominated on its closest side bysoil relatively rich in potassium (K), rare earth elements (RE), and phosphorus (P), called KREEP rocks. These elements, as well as uranium and thorium, would be concentrated in the magma ocean that solidified under the crust of the Moon. There are other models to explain the formation of the lunar mountains, including one published last year in the magazineScience, which suggests that tidal forces, rather than an impact, were responsible for the thickness of the lunar crust.


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