birth of the moon

Prof. Hagai Peretz explains: "Based on dozens of simulations of the formation of planets in the solar system, we discovered that in many cases there is a great similarity between planets and the bodies that hit them. From this we concluded that the similarity between the moon and the earth actually stems from the similarity between Tia - from which the moon was actually formed - and the earth."

Since the dawn of mankind, the moon has aroused great interest in most cultures of the world. He played a central role in the creation of calendars, including the Jewish and Muslim calendars, was considered one of the gods in some pagan traditions and raised many questions regarding his composition, form and manner of formation. These questions have occupied humanity for thousands of years, and even today many children ask themselves - and their parents - if the moon is made of cheese.

In the scientific community, the paradigm of the "giant collision" was established in the 80s, according to which the moon was created by the impact of a celestial body called "Tia" on the earth. In this collision, a lot of material was splashed, some of which began to move around the Earth and gradually crystallized into the moon we know. The question that arises in the face of this theory is whether the same material was displaced from the Earth or from a "tilt".

The possibility that the material was displaced from the Earth was strengthened by the great material similarity between the Earth and the Moon - a similarity found in the analysis of samples brought from the Moon during the "Apollo" missions. However, this possibility goes against existing knowledge, because moons are usually formed from the offending body ("Tia" in this case) and not from the affected body (Earth).

A new study published by Prof. Hagai Peretz from the Faculty of Physics and his colleagues settles the dilemma. "Based on dozens of simulations of the formation of planets in the solar system," explains Prof. Peretz, "we discovered that in many cases there is a great similarity between planets and the bodies that hit them. From this we concluded that the similarity between the moon and the earth actually stems from the similarity between Tia - from which the moon was actually formed - and the earth."
"The meaning is that Tia's history brought it - and not other bodies - close to the Earth," explains researcher Alessandra Mastrobuno-Battisti. "In other words, Tia and the Earth grew in the same area, and therefore formed from similar materials. At some point they did collide with each other, an event that caused a splash of material from Theia, and some of this material later became the moon. In this way, we actually settle between what has been perceived so far as a contradiction between the way moons are formed (from the material splashed from the impacting body) and the similarity between the earth and the moon, which caused the scientific community to mistakenly believe that the moon was formed from the earth and not tilting."