In 2017, a mysterious object was spotted flying through our solar system, sparking fears that it was an alien spaceship .
The object, dubbed ‘Oumuamua, behaved unlike any other seen before, leading experts to classify it as a comet, then as an asteroid, and finally as an interstellar object.
Now, almost two years later, researchers from Yale and Caltech claim that Oumuamua is best viewed as a comet .
Darryl Seligman, who led the study, said: "It has left a number of mysteries in its wake.”
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Researchers believe Oumuamua is a comet
Oumuamua has a small but persistent acceleration, which many astronomers struggled to understand.
But in the new study, the team suggests that this acceleration is caused by the venting of gas that was heated up by the Sun – something that happens regularly for comets.
However, while this venting gives most comets a distinctive ‘tail’, Oumuamua doesn’t have one.
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Mr Laughlin explained: “In the model we’re proposing for ‘Oumuamua, the venting gas does not erupt from a single fixed point on the surface.
“Instead, the jets migrate along the surface, following the warmth and tracking the direction to the Sun.”
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This would mean that Oumuamua rocks back and forth, rather than spinning like a typical comet, according to the researchers.
The team say their discovery suggests that nearly every star in the galaxy could eject similar objects during the planet formation process.
However, further research is needed to confirm this.