4.5 billion years ago, before Earth was even cold enough to support oceans, a Mars-sized fireball slammed into Earth, sending a pile of dust into space. Over time, the debris coalesced, forming the Moon. At least, that’s what the theory goes. But right now, that’s not certain.
According to a new study to be publishedled by planetary scientist Paolo Sossi from the Experimental Planetology Group at the Swiss Federal Institute of Technology (ETH) in Zurich, we have absolutely no irrefutable evidence that such an event ever took place. The specialist online media ScienceAlert tells us more.
This “giant impact” hypothesis makes the Moon one of the most promising elements for understanding the birth and development of our solar system and our planet. As the only permanent natural satellite of the Earth, the Moon helps to stabilize the planet, or even to generate the tides that promote the circulation of the oceans… So far, research suggests that, without it, life on Earth as we know it would have been very different.
So why can’t we just stick with this theory? In the solar system, the rocks on each planet have a unique “fingerprint” of oxygen isotopes (small atoms). However, Paolo Sossi reveals “that since isotopes vary considerably among planetary materials, if there were any evidence of impact, we would expect to see differences in their isotope ratios. Yet no such differences have been detected between Earth and the Moon…” In other words, if there had indeed been this famous collision, the two bodies should have been perfectly mixed, or the Moon should have formed in a different way.
This does not mean that the giant impact did not take place. Only, it cannot be said that it did take place either. Has the origin of the Moon fallen back into the depths of mystery? For Paolo Sossi, the Earth and its natural satellite were simply formed from the same basic material, which eliminates the presence of a hypothetical third body.
While we don’t know how the Earth and the Moon formed from a clump of stardust 4.5 billion years ago, a new way to delve deeper into the question has emerged. It involves studying what’s inside the Moon, and that’s what Paolo Sossi and his colleagues are working on.
“The chemical and isotopic evidence is now strong enough to begin to question the fundamental mechanisms of Moon formationsaid the planetologist. We are also excited to see how geophysical, geochemical and dynamical constraints can be closely linked to provide a new and holistic view of the formation of the Moon.” Ultimately, just when we thought we had regressed on the issue, we may have never been closer to finding a solution to this conundrum.
Source: www.slate.fr
