Gas From the Big Bang May Be Trapped Inside Earth

A team of researchers recently reported that a little over 2 kg of helium-3 leak out of Earth every year, an indication that our planet formed in a solar nebula.
Helium-3 is a very ancient isotope of helium gas; practically all helium-3 emerged from the Big Bang, though some also comes from the radioactive decay of tritium. But the primordial helium-3 — the stuff that synthesized in the aftermath of the Big Bang — ended up in clouds of gas and dust called nebulae that give rise to st