Scientists have offered a “non-alien explanation” for the interstellar visitor known as ‘Oumuamua. 

‘Oumuamua is the first object ever known to have visited our Solar System from outer space. It first zoomed past in 2017, and was deemed so strange that even some serious scientists were convinced it was an alien vessel.

One of 'Oumuamua’s most interesting features is that it lacks a tail and a fuzzy halo - known as a coma - which are normally formed behind comets by dust and gas warming in the Sun's heat.

Additionally, once 'Oumuamua slingshotted around the Sun, it appeared to speed up and deviate from its expected trajectory, propelled by a mysterious force on its way out of the Solar System.
This type of acceleration is typically associated with the release of trapped gas from a material, as seen in comets. 

However, 'Oumuamua displays no further typical tracers of cometary activity such as a ‘tail’ of dust or gas. These seemingly contradictory observations have made it difficult for researchers to precisely define the nature of ‘Oumuamua.

A new study published this week suggests the unreconciled acceleration of the interstellar object is due to the production of hydrogen gas from ice reserves.

An advanced computer model was used to attribute the acceleration of ‘Oumuamua to the release of trapped molecular hydrogen from within the object. That hydrogen could have been formed through energetic processing of water-rich ice as the body passed close to the Sun, and is subsequently released from the object, slightly bending its path through our Solar System. 

Such reactions have been demonstrated in existing experimental work, showing that molecular hydrogen is known to be produced and subsequently expelled under such conditions. 

The findings support previous theories that ‘Oumuamua may have originated as an icy planetesimal - a small object formed during the early stages of planet formation - similar to Solar System comets.

The study is accessible here.