Comet or asteroid? Scientists ID interstellar visitor

June 27, 2018 by Marcia Dunn
Comet or asteroid? Scientists ID interstellar visitor
This artist's rendering provided by the European Southern Observatory shows the interstellar object named "Oumuamua" which was discovered on Oct. 19, 2017 by the Pan-STARRS 1 telescope in Hawaii. In the Wednesday, June 27, 2018 edition of the journal Nature, a European-led team makes the case it is a comet, not an asteroid. (M. Kornmesser/European Southern Observatory via AP)

Last year's visitor from another star system—a cigar-shaped object briefly tumbling through our cosmic neck of the woods—has now been identified as a comet.

A European-led team makes the case in Wednesday's edition of the journal Nature.

Telescopes first spotted the mysterious red-tinged object last October as it zipped through the inner solar system. Since then, astronomers have flip-flopped between and asteroid for our first confirmed interstellar guest.

Neither a coma nor tail was spotted, hallmarks of an icy comet. But Italian astronomer Marco Micheli and his team reported that the object's path and acceleration are best explained not just by gravity, but also gases shedding from a comet.

The release of what's believed to be gaseous carbon monoxide, carbon dioxide and water applied only a tiny force on the known as Oumuamua—about 1,000 times smaller than the effect of the sun's gravity—and barely altered its path, the researchers said.

This video explains how observatories, including NASA’s Hubble Space Telescope, found that ‘Oumuamua gained an extra boost of speed, likely from comet-like jets of gas. Credit: NASA

But the team's measurements "were so precise that we could actually see the change in position caused by the outgassing," said co-author Paul Chodas, manager of NASA's Center for Near-Earth Object Studies at Jet Propulsion Laboratory in Pasadena, California.

"It's a definitely exciting discovery," said Micheli of the European Space Agency .

This artist's impression shows the first interstellar object discovered in the Solar System, `Oumuamua. Observations made with the NASA/ESA Hubble Space Telescope and others show that the object is moving faster than predicted while leaving the Solar System. Credit: ESA/Hubble, NASA, ESO, M. Kornmesser

Micheli said computer models suggest objects typically are ejected during the formation of planetary systems, and that most of these castaways should be comets given their location on the frigid outskirts of their systems. Only a tiny fraction should be asteroids, by scientists' best calculations.

Had it been an asteroid, it would have been "extremely lucky to beat these odds"—or it would have underscored scientists' misunderstanding of the early solar system, Micheli said.

Discovered by a telescope in Hawaii, Oumuamua is Hawaiian for messenger from afar arriving first, or scout.

This animation shows the path of `Oumuamua as it passed through the inner solar system, and its location on Jan. 2, 2018, when it was last observed by NASA's Hubble Space Telescope. By then, 'Oumuamua had been boosted by 25,000 miles (40,000 kilometers) compared to where it would have been if only gravitational forces were affecting its motion. Credit: NASA/JPL-Caltech

It's long gone, as are the chances of knowing conclusively what it was.

The University of Toronto's Alan Jackson, who reported in March that Oumuamua likely came from a two-star system, remains unconvinced of its true identity.

"But this is certainly an interesting new piece of information for us to chew on," he said in an email.

Explore further: 'Oumuamua likely came from a binary star system

More information: Marco Micheli et al. Non-gravitational acceleration in the trajectory of 1I/2017 U1 ('Oumuamua), Nature (2018). DOI: 10.1038/s41586-018-0254-4

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2 / 5 (4) Jun 27, 2018
"In its beginning, every (historic) object is a comet. When an object has made enough number of orbits near a star, it has lost the most of its volatile elements. The objects with a minimum of volatile elements are called asteroids or solid (rocky) objects. Those objects that have not been approaching closer to a star possess the elements' structure of the lower order, which is typical for a cold or colder space. "
1 / 5 (5) Jun 28, 2018
I call it a derelict star ship, but its course changes say maybe still under control of some kind of piloted navigation. Possibly by computer, this ship may have been sent by another civilization that has yet to develop warp drive or its attendant enabling technologies, given its slow speed. Of course, like Steven Hawking said, slow ships take many thousands of earth standard years to reach even near stars. Sooo, maybe the signal that prompted the dispatch of this robot ship came during a previous iteration of Earth advanced civilization maybe in the next last or even previous ice age cycle. We have no idea of the complete archaeology under our feet, much less our oceans. Cities under hundreds of meters of water in Chinese lakes and classified by the Chinese military last saw the light of day at least 60,000 y.a. and rival today's civic design.
1 / 5 (1) Jun 28, 2018
Onan, you have never met a gullible belief you fail to swallow whole. Obvious that when Isis reassembled you? She forgot to include any brains. That canoptic jar must have been lost?

Considering how many billions of years ago this knapped remnant was flung out of it's original star system? The signal must have been sent by the advanced technology of Archaean slime. Oh yeah, that makes perfect senseless.
5 / 5 (3) Jun 29, 2018
Fermi's paradox in a nutshell> the team's measurements "were so precise that we could actually see the change in position caused by the outgassing

It's not in solar orbit but from another solar system
Wandering from star to star with no propulsion engine on to its next star, as we are according to Fermi's paradox we are the only life in the entire universe, what are the chances of Oumuamua encircling our sun on its journey of our galactic trillion stars.
According to Fermi's paradox absolutely less than zero
1 / 5 (1) Jun 29, 2018
well g, another way to consider the odds? What are the odds against a random piece of stellar reject would not pass through this particular star system? Over billions of years of time? Considering there are gazillions of similar debris flying about in every direction.

The astronomers researching this event. Pointed out this must occur with a monotonous regularity. However it is only recently that they have begun developing the instrumentation sophisticated enough to detect such brief visits by fast-moving cosmic intruders.

If it helps you visualize such unbelievably random odds of occurring? Think of how many sperm over how many years, did your daddy shoot off? And only one single sperm out of how many? Sprinted ahead of all the competition. Ramming the egg. to produce you, specifically.
not rated yet Jul 03, 2018
Upon reading the paper from Micheli, it shows that this object's acceleration is >90 percentile of all observed comets. Rare company. In addition, it is very rare to have an accelerating comet with no visible dust. Together, very rare indeed.

Although I find the comet explanation plausible, it is certainly very convenient.

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