Interstellar visitor gets a speed boost

’Oumuamua is unexpectedly accelerating on its way out of our Solar System

The more we learn about ’Oumuamua – the mysterious interstellar object that has been travelling through our cosmic neighbourhood for the past few months – the stranger it seems. It is currently heading out of our Solar System after sweeping past the Sun in September 2017, but it has strayed from its predicted path. It has travelled around 40,000 kilometres further than it should have if affected by gravitational forces alone.

‘Oumuamua was originally thought to be a comet before being classed as an asteroid. However, the recent speed boost has led to it being reclassified as a comet once more. It is thought that its acceleration is the result of outgassing (the ejection of gas and dust when warmed by the Sun), a behaviour that has been observed in other comets.

Astronomers have been carefully observing ‘Oumuamua since its discovery using both ground-based observatories and the Hubble and Spitzer space telescopes