Until now, scientists assumed that the planets formed slowly. In the dust cloud around the sun, the grains collide and compress to become larger and larger—until protoplanets formed, the gravity of which attracted smaller debris. This process took about a hundred million years.
But Helium 3 escapes from the depths of the Earth suggests a different scenario, say scientists in a work published in “Geochemistry, Geophysics and Geological Systems”.
According to them, larger rocks very quickly began to attract small crumbs, which were drawn by the sun from the vicinity of the cloud. The whole process was fast and took one to two million years. This means that the gases from the cloud around the Sun, dissolved in molten rock, did not have time to escape from the young and hot Earth.
The key to solving the mystery is a rare isotope of helium. This gas occurs in nature in two forms (isotopes). There are two protons in each helium nucleus. In the lighter nucleus of helium-3, there is also a neutron, in the heavier nucleus of helium-4 there are two neutrons.
there where Earth’s crust It is the thinnest and the “heat plumes” of its mantle reach it, and gases dissolved in the rocks are released, including helium. The heavier helium 4 is no surprise. It is produced continuously by the decay of radioactive elements (mainly uranium and thorium). However, helium-3 can only come from the primordial cloud around the young sun.
Hel-3 is so light that if the Earth had formed a hundred million years ago, it would have all escaped into space. In addition, it would have evaporated during a cosmic collision, when a Mars-sized object (called Theia) smashed into it tens of millions of years after the formation of the Earth. The collision re-dissolved Earth’s rocks, resulting in the formation of the Moon. The light gas should go to outer space.
