'Oumuamua: Alien Interstellar Object Is Coated in an Organic Layer That Protects Its Icy Core From the Sun

Oumuamua, here in an artist’s rendering, is long and thin like a cigar instead of a more typical lumpy shape, and it’s not giving off the cloud of evaporating gas that scientists expected to see. ESO/M. Kornmesser

The mysterious 'Oumuamua has been slowly making its way through our solar system since astronomers first noticed it in October. Scientists are still debating whether the object—the first interstellar body known to visit the Milky Way—is an asteroid, a comet or even a giant alien spacecraft.

Now scientists have modeled the bizarre visitor and discovered that it's covered in a rich, organic coating, which might protect a freezing, water-rich interior from the sun. Alan Fitzsimmons from Queen's University Belfast, U.K, and colleagues published the findings Monday in Nature Astronomy.

'Oumuamua's composition

Measuring visible and near-infrared wavelengths using spectroscopy, the team determined what stuff likely makes up the strange interstellar visitor. This information sheds light on the origins of bizarre objects like 'Oumuamua.

"Spectroscopy allows us to discern the types of materials on the surface of an object and what it is made of," Fitzsimmons told Newsweek. "In this case it also allowed us to rule out some possibilities, such as minerals commonly found on rocky asteroids.

"Our data show the outer layers have been blasted by cosmic rays during 'Oumuamua's voyage between the stars, while the inside will have been kept at the frigid temperatures of interstellar space," he said.

Without a nearly 2-foot-thick layer of organic material, 'Oumuamua's icy comet-like core could have been vaporized when it passed close to the sun earlier this year.

Origins of the mysterious visitor

These observations support previous ideas about the origins of interstellar objects, Fitzsimmons told Newsweek.

"It looks like our general ideas of how interstellar objects are created may be correct after all. We expected most come from the icy outer regions of other solar systems, and that's what our data support."

Is 'Oumuamua an alien spacecraft?

One of the reasons for astronomers' fascination with 'Oumuamua is its strange cigar-like shape. Long and thin, its shape is one of the reasons why it is being investigated as a potential alien spacecraft. "I would say that probability must be very small that ['Oumuamua is] artificial," astronomer Avi Loeb of Harvard University and the Breakthrough Listen project told Newsweek last week. "But at the same time there's always the first, and that's why we should check without the prejudice."

On Friday, however, a note published by the American Astronomical Society claimed the shape may simply be due to abrasion from a continual barrage of tiny particles over hundreds of millions of years.

12_18_Gomboc asteroid figure
Mathematical modeling of an 'Oumuamua battered by tiny particles. Gábor Domokos et al/American Astronomical Society

"We currently do not know where the asteroid came from—what was its exact path—so we cannot reconstruct its exact history. Nevertheless, it is certain that it has been continuously bombarded by micrometeorites," Gyula M. Szabó, director of the Gothard Astrophysical Observatory of Eötvös University and co-author of the note, said in a press release. "This abrasion process, if sufficiently long, would lead to the currently observed shape, regardless of the asteroid's initial geometry and this theory offers a natural and plausible explanation for the bizarre shape of 'Oumuamua."

Unfortunately for alien hunters, today's spectroscopy data doesn't really support the idea of a giant interstellar spacecraft either, Fitzsimmons told Newsweek. "If it was intelligent life," he adds, "why haven't they invented windows?"