Interstellar asteroid 'Oumuamua has a crust but no aliens

Scientists have been studying the strange space rock from beyond our solar system. There's plenty of weirdness, but no signs of E.T. aboard ... so far.

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Eric Mack
2 min read

The first object to visit our solar system from beyond the pull of our sun's gravity is starting to come into focus. 

Astronomers have scrambled over the past several weeks to study the asteroid, or comet-like object dubbed "'Oumuamua," as it dropped into our cosmic neighborhood, made a turn around the sun and then sped back out to deep space.


This artist's impression shows 'Oumuamua, an interstellar asteroid.

ESO/M. Kornmesser

Early results paint a picture of a weirdly oblong, skyscraper-sized rock. It isn't sending out any of the signals we would expect from an interstellar spacecraft, but it does have a crust.

"A half-meter thick coating of organic-rich material (observed on 'Oumuamua) could have protected a water-ice-rich comet-like interior from vaporizing when the object was heated by the sun, even though it was heated to over 300 degrees centigrade," explained Professor Alan Fitzsimmons from Queen's University Belfast, in a release. "We have discovered that the surface of 'Oumuamua is similar to small solar system bodies that are covered in carbon-rich ices."

In other words, a dry crust built up over millions or even billions of years might conceal the space rock's wet "guts," kind of like the dry crust on a loaf of bread hides the moist goodness within.

"We've discovered that this is a planetesimal with a well-baked crust that looks a lot like the tiniest worlds in the outer regions of our solar system, has a greyish/red surface and is highly elongated, probably about the size and shape of the Gherkin skyscraper in London," explained Dr. Michele Bannister, who also led the research with Fitzsimmons.   

The research is published Monday in the journal Nature Astronomy and describes an object that is fascinating but seems to be of a natural origin. The publication comes just a few days after initial results from the Breakthrough Listen project targeting 'Oumuamua with the Green Bank Radio Telescope found no signs of extraterrestrial signals or intelligence.

Hopes that the object may actually be a visiting spacecraft from a distant star seem to be fading fast. 

But astronomer Ray Norris from Western Sydney University in Australia says while 'Oumuamua is most likely a big rock, we can't yet eliminate the possibility that it is a product of some sort of intelligent design.

"We cannot discount the possibility that it really is a spacecraft," he wrote Monday in The Conversation. "Perhaps one that got into trouble a long time ago and its corpse continues to tumble for eternity through the vastness of interstellar space."

Odds are, though, that many of the details of the odd visitor will remain a mystery as it continues to speed further away from us for the foreseeable future. 

Unless, of course, it has the ability to "turn on" and make one very impressive U-turn.

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