|Manu||Date: Friday, 01-April-2022, 4:41 PM | Message # 1|
|Ancient helium leaking from core offers clues of Earth's formation|
by American Geophysical Union
Helium-3, a rare isotope of helium gas, is leaking out of Earth's core, a new study reports. Because almost all helium-3 is from the Big Bang, the gas leak adds evidence that Earth formed inside a solar nebula, which has long been debated.
Helium-3 has been measured at Earth's surface in relatively small quantities. But scientists did not know how much was leaking from the Earth's core, as opposed to its middle layers, called the mantle.
The new study pins down the core as a major source of helium-3 on the Earth. Some natural processes can generate helium-3, such as the radioactive decay of tritium, but helium-3 is made primarily in nebulae—massive, spinning clouds of gas and dust like the one that gave rise to our Solar System. Because helium is one of the earliest elements produced in the universe, most helium-3 can be traced back to the Big Bang.
As a planet grows, it accumulates material from its surroundings, so its composition reflects the environment in which it formed. To get high concentrations of helium-3 deep in the core, Earth would have had to form inside a thriving solar nebula, not on its fringes or during its waning phase.
The new research adds further clues to the mystery surrounding Earth's formation, lending additional evidence to the theory that our planet formed inside the solar nebula.
The study was published in the AGU journal Geochemistry, Geophysics, Geosystems, which publishes research on the chemistry, physics, geology and biology of Earth and planetary processes.
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