A new study suggests that an extremely rare type of helium that was created soon after the Big bang is leaking out of Earth's metallic core.
The majority of the gas in the universe is primordial and was created about 13 billion years ago. The solar system is thought to have been created by the creation of a large, spinning cloud of gas and dust.
The researchers said that the discovery that Earth's core likely contains a huge amount of helium-3 supports the idea that Earth formed inside a thriving solar nebula.
Helium is a wonder of nature, and a clue for the history of the Earth, that there is still a significant amount of this isotope in the interior of the Earth.
Helium-3 has a single neutron instead of the usual two in its nucleus. It is a rare gas, making up less than 1% of the total amount of helium on Earth. It comes from the decay of tritium, a rare radioactive isotope of hydrogen. Most of the elements in the universe came from the Bigbang.
The researchers wrote in the study that they already knew that about 2 kilograms of helium-3 escapes from Earth annually, mostly along the mid-ocean ridge system.
This is enough to fill a balloon the size of your desk.
Scientists weren't sure how much of the helium came from the core and how much came from the mantle.
The research team modeled the abundance of helium during two important phases of Earth's history, the planet's early formation and the formation of the moon. The moon is thought to have formed when a huge object about the size of Mars collided with Earth.
This event would have melted the Earth's crust and allowed much of the helium inside to escape.
At that time, Earth did not lose all of its helium-3. It still has some of the rare gas that goes out of Earth. The researchers wrote in the study that the core is less vulnerable to large impacts compared to other parts of the Earth system.
The researchers combined the modern leak rate with the models of helium isotope behavior. The calculations show that between 10 and 2 trillion pounds of the gas are hanging out in the core of the planet.
The metallic core is believed to be a leak that supplies the rest of the Earth with helium.
The results are not ironclad because they are based on modeling. The team had to make a number of assumptions, for example, that Earth took on helium as it formed in the solar nebula, and that some of it left the core for the mantle. The scientists said that the assumptions made about how long the solar nebula lasted relative to the rate at which Earth formed mean that there may be less helium-3 in the core than they calculated.
The researchers want to find more clues that support their findings. If hydrogen is leaking from Earth at the same rate as helium-3, it could be a smoking gun that the core is the source.
It was originally published on Live Science.
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