The Earth contains many mysteries about how it formed, and what is at its centre. A recent study has clues as to what shaped our planet and solar system. Scientists say vast amounts of a primordial form of the gas helium may be trapped inside Earth. It is called helium-3. Scientists believe it is from a giant cloud of gas and dust that gelled to create different planets. It has been inside Earth's core for billions of years. It is occasionally released in volcanic eruptions.

The research is very exciting for planetary geologists. They think the helium-3 could unlock secrets of the Big Bang. The presence of helium-3 could mean that Earth was created faster than we thought. A geophysicist in the USA said: "There is evidence that has been interpreted to say the Earth formed very slowly, requiring 100 million years. [However], you wouldn't get much helium deep in the Earth if the Earth formed that slowly."