'Super earths' outside our solar system that are rich in hydrogen or helium may be even more habitable than our own planet, a new study suggests.

Researchers say rocky exoplanets with atmospheres dominated by hydrogen and helium have surfaces warm enough to host liquid water.

Researchers say rocky exoplanets – planets outside our Solar System – with primordial atmospheres dominated by hydrogen and helium have surfaces warm enough to host liquid water.

Most orbit other stars, but free-floating exoplanets, called rogue planets, orbit the galactic center and are untethered to any star.

Therefore, all planets built up atmospheres that were dominated by these two elements, including Earth. 

When our planet first formed from out of cosmic of gas and dust, it collected an atmosphere consisting mostly of hydrogen and helium – a so-called primordial atmosphere 

However, other, more massive planets can collect much larger primordial atmospheres, which they can keep indefinitely in some cases

'Such massive primordial atmospheres can also induce a greenhouse effect – much like Earth’s atmosphere today,' said Helled

While on Earth, this geothermal heat plays only a minor role for the conditions on the surface, it can contribute more significantly on planets with massive primordial atmospheres

Most orbit other stars, but free-floating exoplanets, called rogue planets, orbit the galactic center and are untethered to any star (file photo) 

'What we found is that in many cases, primordial atmospheres were lost due to intense radiation from stars, especially on planets that are close to their star,' said Marit Mol Lous, PhD student and lead author.