the old primordial helium which was forged as a result of the Big Bang escaping from the Earth’s core, scientists report in a new study.
But rest assured, there is no cause for alarm, experts say, the earth does not deflatebut this discovery is confirmation of a hitherto unresolved detail about the birth of our planet: Earth formed inside a solar nebula, the same molecular cloud that gave rise to the Sun.
Another thing this study suggests is that other primordial gases may seep from the Earth’s core into the mantle, which in turn could provide information about the composition of the solar nebula.
Helium on Earth comes in the form of two stable isotopes. Lot, the most common is helium-4whose nucleus contains two protons and two neutrons. Helium-4 makes up about 99.99986% of all helium on our planet.
The other stable isotope, which makes up about 0.000137% of Earth’s helium, it’s helium-3, with two protons and one neutron.
Helium-4 is primarily the product of radioactive decay of uranium and the thorium, which is happening right here on Earth. In contrast, helium-3 is primarily primordial, formed in the moments following the Big Bang, but can also be produced by the radioactive decay of tritium.
This is the detected gas escaping from the earth’s corethe isotope Helium–3which mainly infiltrates along the mid-ocean volcanic ridge system, which gives us a good indication of how fast it is escaping from the crust.
This rate is about 2,000 grams per year: “enough to fill a desk-sized globe”, explains geophysicist Peter Olson of the University of New Mexico.
“It is a wonder of nature and a clue to Earth’s history that there is still a significant amount of this isotope inside the Earth.” add.
What is less clear is the provenance; how much helium-3 could come out of the core, compared to how much is in the mantle.
That would tell us the source of the isotope. When the Earth formed, it did so by accumulating materials from the dust and gas that floated around the newborn Sun.
The only way significant amounts of helium-3 could be inside the planetary core is if it formed into a blooming nebula. That means, not at its periphery, and not while it was dissipating and flying.
Olson and his colleague, geochemist Zachary Sharp of the University of New Mexico, studied by modeling the Earth’s helium inventory as it changes. First, how it formed, the process during which the protoplanet accumulated and incorporated helium; then after the Big Impact.
This, astronomers think, occurred when a Mars-sized object collided with a very young Earth, sending debris flying into Earth’s orbit, which eventually recombined to form the Moon.
During this event, which would have remelted the mantle, a large part of the helium locked up in the mantle would have been lost. The core, however, is more impact-resistant, suggesting it could be a fairly efficient reservoir for holding helium-3.
The Sun is thought to have formed in a cloud like the Lagoon Nebula and this latest discovery suggests Earth too (ESA/NASA)
In fact, that’s what the researchers found. Using the current rate at which helium-3 leaks from the interior, along with models of the behavior of helium isotopes, Olson and Sharp found that there are likely 10 teragrams (10,000 billion grams) per petagram (100 million tons) of helium. -3 at the heart of our planet.
This suggests that the planet must have formed within a thriving solar nebula and did not “join” the solar system after it formed. However, several uncertainties remain. The probability that all of the conditions for helium-3 sequestration in the Earth’s core are met is moderately low, meaning there could be fewer isotopes than the team’s work suggests.
However, it is possible that there is also abundant primordial hydrogen in our planet’s core, trapped in the same process that may have accumulated helium-3. Looking for evidence of hydrogen leakage could help validate the findings, the researchers say.