Oumuamua: Did an alien spaceship just pass through our solar system? It’s unlikely, experts say


Updated

November 07, 2018 12:08:51

Experts have expressed scepticism about claims from two Harvard astronomers who say an interstellar object that passed through our solar system in late 2017 and early 2018 could have been part of an alien spacecraft.

Key points:

  • Study suggests ‘Oumuamua is not an “active comet” and could be a “discarded light-sail of extra-terrestrial origin”
  • The interstellar object was first discovered in October 2017, and measured less than 400 metres in diameter
  • Other experts have expressed scepticism over the study’s findings

Shmuel Bialy and Abraham Loeb, two astronomers from the Harvard Smithsonian Centre for Astrophysics, suggested the cigar-shaped object — given the Hawaiian name ‘Oumuamua, which NASA notes “means a messenger from afar arriving first” — could have been a discarded light sail of extra-terrestrial origin, perhaps sent here on purpose.

Similar to how a sailing boat uses the wind in its sail to push it forward, a spacecraft with a light sail uses the light from a nearby star to propel it, with radiation pressure exerting a tiny amount of force.

“Recent observational and theoretical studies imply that ‘Oumuamua is not an active comet,” the researchers said in a draft version of their study.

“If radiation pressure is the accelerating force, then ‘Oumuamua represents a new class of thin interstellar material, either produced naturally, through a yet unknown process in the [interstellar medium] or in proto-planetary disks, or of an artificial origin.”

They said it seemed to use the Sun’s radiation as an energy source, and even if it was only a natural object, it was still unique.

But Alan Jackson, a fellow at the Centre for Planetary Sciences at the University of Toronto Scarborough, told CNN the study was “distinctly lacking in evidence, never mind extraordinary evidence” and that the spectral data suggested the object was an asteroid or comet.

“Any functional spacecraft would almost certainly retract its solar sail once in interstellar space to prevent damage,” Mr Jackson said.

“The sail is useless once away from a star so there would be no reason to leave it deployed.

“If it was then deployed again on entering the solar system it would be pristine. Even if it was left deployed the dust accumulation would be primarily on the leading side like bugs on a windshield.”

Astrophysicist Katie Mack also expressed scepticism about the study, encouraging Twitter users to exercise caution when reading “huge if true” claims.

‘Oumuamua originated outside solar system

In late October, 2017, NASA said the recently discovered interstellar visitor appeared “to have originated from outside the solar system, coming from somewhere else in our galaxy”.

“This unusual object … is less than [400 metres] in diameter and is moving remarkably fast,” NASA said at the time.

“Astronomers are urgently working to point telescopes around the world and in space at this notable object.

“Once these data are obtained and analysed, astronomers may know more about the origin and possibly composition of the object.”

NASA’s Centre for Near-Earth Object Studies scientist Davide Farnocchia, who works at the agency’s Jet Propulsion Laboratory in California, said it was “the most extreme orbit” he had seen.

“It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back,” Mr Farnocchia said shortly after its discovery.

Topics:

spacecraft,

astronomy-space,

united-states

First posted

November 07, 2018 12:05:53





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