spaceSpace and Physics

This Is Our First Look At The Interstellar Object That Flew Through Our Solar System


Jonathan O'Callaghan

Senior Staff Writer

The object A/2017 U1. Queen's University Belfast

This is probably the first image of an interstellar object we’ve ever seen in our Solar System.

Last week, we were treated to the news that A/2017 U1 may be an asteroid or comet from another star, which had been flung in our direction.


Now, scientists have used telescopes around the world to track the object, verifying its extraterrestrial origins and getting our first glimpse at what it looks like.

"By Wednesday [last] week it became almost certain this object was alien to our Solar System,” Professor Alan Fitzsimmons from Queen’s University Belfast, who is part of the project to study the object, said in a statement. “We immediately started studying it that night with the William Herschel Telescope in the Canary Islands, then on Thursday night with the Very Large Telescope in Chile."

The team were able to snap clear images of the object and get data on its chemical composition. It seems to have a red color, similar to objects found in the Kuiper Belt in the outer Solar System.

It’s thought to be about 400 meters (1,312 feet) across, and traveling in a highly eccentric orbit. A hundred years ago, it’s thought the object was 559 times further from the Sun than Earth (559 Astronomical Units, or AU). On October 14, it passed just 0.161 AU from Earth, making its closest approach to the Sun on September 9 of 0.25 AU before swinging out again, likely never to return.


Fitzsimmons told IFLScience that more images and data were on the way about the object. But all the data suggests at the moment that it was indeed interstellar.

“Basically, it is traveling significantly faster than the escape velocity from the Sun,” he said. Its orbit suggests it will not return again.

Data so far suggests this was a small rocky or icy object, which has been drifting through our galaxy for millions or billions of years. Unlike comets in our Solar System, there’s no evidence of a coma of dust and gas, suggesting this may be an asteroid and not a comet.

By chance, it appears to have flown into our Solar System, and is now on its way out into interstellar space.


We’ve thought such objects might exist, but this is the first time we’ve ever seen one. It was probably thrown out of another star system during its planet formation period.

It’s a groundbreaking finding, and now we’ve got a good look at its appearance. There will be more news about this object in the future though, for sure.


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