Oxygen around comet reveals Solar System’s ‘gentle’ birth

The Rosetta spacecraft has "sniffed" molecules of oxygen surrounding the comet it is tracking in what scientists have called their most surprising discovery yet.

The find means long-standing theories on how our Solar System was formed could be wrong.

The study, published in the journal Nature, used Rosetta to probe the atmosphere of the Comet 67P/Churyumov-Gerasimenko.

Researchers found oxygen was one of the most common gasses around the comet.

Professor Kathrin Altwegg said her fellow scientists were amazed by the discovery, BBC reports.

"When we first saw it, we went a little bit into denial because it is not what you would expect to find on a comet," she said.

The findings were so unusual because oxygen rarely stays in its unique form, preferring to react with other elements and form compounds.

Lead author of the study Andre Bieler said the presence of oxygen suggests the solar system was formed in a slow and steady process.

"All the models say it shouldn't survive for so long, which tells us something about the building of our Solar System - it has to be very gentle to build these ice grains, it seems it is a pretty pristine material still."

Current ideas on how the Solar System was formed do not allow for the conditions that would have allowed oxygen to be incorporated into the nucleus during Comet 67P’s formation.