Where does the gold on Earth come from? A series of large random impacts could have provided iron-related elements such as gold, rhenium and osmium to the Earth’s mantles, according to a study by the Southwest Research Institute and the NASA Lunar Science Institute in Boulder (United States) that it was published in the journal Science in 2010. Furthermore, our planet would not have been the only recipient of these minerals, since our neighboring planet Mars and the Moon would also have acquired them in a similar way. In addition, the researchers responsible for the study suggested that these collisions could also be the origin of the water on the Moon.
To reach these conclusions, the team of researchers carried out a series of computer simulations that indicated that approximately 4,500 billion years ago, a small number of strong random impacts on the surface of our planet were the responsible sources of these minerals on Earth. . They were rocky objects that arrived in the planetary phase of our solar system.
The scientists, led by William Bottke, stressed that the relative abundance of iron-like elements on Earth, the Moon and Mars can only be explained if the impacts on these planets were relatively large . The largest of these impacts on Earth would have been roughly the size of Pluto: more than 3,000 kilometers across. In addition, the authors point out that these impacts probably occurred after the metal cores of the celestial bodies were formed , since otherwise these elements would have joined with the metallic iron of the core and disappeared from the planetary upper layers.
“These elements reveal to us what was ‘hitting’ our planet at that time,” explained William Bottke of the Southwest Research Institute in Boulder, Colorado, and leader of the research. On the other hand, only one thousandth of these materials are observed on the Moon with respect to the Earth. According to the study, these differences can be explained because we are talking about a very limited number of impacts. A huge object might not reach the smaller Moon, but crash into our planet, creating the discrepancies in the abundance of metals that we observe today.
Some of these impacts could have altered the tilt of the Earth’s axis , brought water to the Moon’s mantle, and possibly even helped produce the orbital tilt of our satellite.
