This artist’s impression shows the first interstellar asteroid: `Oumuamua. This unique object was discovered on 19 October 2017 by the Pan-STARRS 1 telescope in Hawai`i. Subsequent observations from ESO’s Very Large Telescope in Chile and other observatories around the world show that it was travelling through space for millions of years before its chance encounter with our star system. `Oumuamua seems to be a dark red highly-elongated metallic or rocky object, about 400 metres long, and is unlike anything normally found in the Solar System.
A long time ago, in a galaxy far, far away…an unusually shaped object began its journey toward our solar system. Discovered on October 19, 2017 by the University of Hawaii’s PanSTARRS1 telescope, the first verified interstellar object was originally classified as a comet.
However, further observations revealed no cometary activity. It was then thought to be an unknown type of asteroid. But as it zipped past our sun, it accelerated slightly, leaving scientists scratching their heads.
Named Oumuamua by its discoverers, the first object known to come from outside out solar system was measured to be a quarter mile long. Observations confirmed it to be ten times as long as it is wide. Its unusual cigar shape is unlike any asteroid or comet so far discovered.
“For decades we’ve theorized that such interstellar objects are out there, and now—for the first time—we have direct evidence they exist,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate in Washington.
By using four different filters from the FORS instrument on the ESO Telescope, astronomers were able to determine that Oumuamua varies in brightness by a factor of ten as it spins on its axis every 7.3 hours.
“We also found that it had a reddish color, similar to objects in the outer solar system, and confirmed that it is completely inert, without the faintest hint of dust around it,” said Karen Meech of the Institute of Astronomy in Hawaii.
This suggests that the interstellar interloper is composed of rock and metals, making it very dense. Because no water-ice was detected, the most likely cause of its surface reddening is due to cosmic ray irradiation over hundreds of millions of years.
By studying the trajectory, astronomers have been able to deduce that Oumuamua likely came from the vicinity of the star Vega. But 300,000 years ago, when this unusual object made its journey from that area, Vega was not there.
This means that the Vega system is not the origin of our strange visitor.
“What a fascinating discovery this is! It’s a strange visitor from a faraway star system, shaped like nothing we’ve ever seen in our solar system neighborhood,” said Paul Chodas of the Center for Near-Earth Object Studies at NASA’s Jet Propulsion Laboratory.
Recent theories by a duo of researchers at Harvard Smithsonian Center for Astrophysics have raised the idea that Oumuamua might be artificial in origin.
The theory is based on its unexpected acceleration in January 2018, as it traveled through our solar system.
In a paper submitted to the Astrophysical Journal Letters, the two scientists wrote, “Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization.
Light-sails with similar dimensions have been designed and constructed by our own civilization, including the IKAROS project and the Starshot Initiative. The light-sail technology might be abundantly used for transportation of cargos between planets or between stars.
This would account for the various anomalies of Oumuamua, such as the unusual geometry inferred from its light-curve, its low thermal emission, suggesting high reflectivity, and its deviation from a Keplerian orbit without any sign of cometary tail or spin-up torques.”
But Oumuamua isn’t the first-time astronomers have thought they’d found proof of extraterrestrial existence. Back in 1977, the WOW signal was detected by Ohio State University’s Big Ear telescope; the origins of which are still debated by scientists. And everyone has heard of Tabby’s Star: located in the constellation Cygnus about 1,470 light-years from Earth, whose brightness randomly fluctuates for unknown reasons, giving rise to theories of Dyson’s Spheres or an alien armada.
Fascinating theories aside, it is also possible that this visitor from afar is stellar fragment from a long ago violent super nova explosion, a piece of a rocky planet destroyed by an impact from another larger object, or any number of natural—as-of-yet unknown—origins. Just because an object like this hasn’t been detected in our solar system before, and its shape is unusual, doesn’t mean it is of artificial design.
There is so much about our cosmos that we still don’t know, so much to still be discovered.
With a fitting name meaning “a messenger from afar arriving first,” what are your thoughts on its origins?