Leftover debris from the Earth generated craters on the Moon

The asteroid bombardment recorded in the Luna 3.9 billion years ago it has its origin in a process of continuous impacts that remained from the main phase of formation of the Land.

The planetologists of the University of Münster (Germany) They have opted for this hypothesis to explain the Late Heavy Bombardment of the Moon or LHB, to the detriment of the one that suggests that instabilities in the orbits of the gas giant planets caused a sudden and abrupt increase in the impacts of asteroids and comets in the solar system. Exterior.

The research has been based on very precise isotopic measurements of lunar rocks formed during the bombardment 3.9 billion years ago, or about 500 million years after the formation of the Moon. The results are published in the current issue of the journal “Science Advances”.

These rocks contain tiny globules of metal that consist of material from impactor asteroids. By studying the isotopic composition of these metal globules, researchers can determine where in the solar system these bodies originated.

They focused on the elements ruthenium and molybdenum because these elements show systematic changes in their isotopic composition depending on where they formed in the solar system.

“Our research shows that the bombardment of the Moon was by the same bodies that formed the Earth and the Moon.”, explains the planetologist and lead author of the study, Dr. Emily Worsham.

Impact craters on the Moon, therefore, are due to a continual bombardment of asteroids left over from the Earth’s main phase of formation. This also allows scientists to rule out a sudden increase in impact rate due to bombardment with bodies from the outer solar system. But then where did the 3.9 billion year age grouping come from?

“It has been previously suggested that the lunar rocks studied so far are composed mainly of material from a single impact basin: the Mare Imbrium on the north-central side of the Moon facing Earth.”, Explain Emily Worsham.

It is known from theoretical calculations that the orbits of the gas giants changed at some point in the early history of the solar system, scattering a large number of bodies from the outer solar system to the interior, which collided with the Earth and the Moon, between others.

“This event must have taken place earlier than previously thought, because we found no evidence of asteroid or comet impacts from the outer reaches of the solar system on lunar rocks.” explains Professor Thorsten Kleine. Therefore, the change in the orbits of the gas giant planets probably took place during the main formation phase of the Earth-like planets, that is, in the first approximately 100 million years of the solar system, which in turn once agrees well with recent dynamic models.

“Our study, therefore, also shows that Earth-like planets incorporated water-rich bodies from the outer solar system relatively early, during their formation, thus creating the conditions for the emergence of life.” agrega Thorsten Kleine.