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The First-Known Interstellar Asteroid is Like a Giant Tumbling Torpedo
Artist’s impression of the 400-meter-long interstellar asteroid 1I/2017 U1 `Oumuamua. Credit: ESO/M. Kornmesser.
Remember that comet-no-wait-asteroid astronomers discovered in October on a high-velocity hyperbolic orbit around the Sun? It has been determined that the object must be of interstellar origin and, based on follow-up observations over the past several weeks, it’s shaped like nothing that’s ever been seen before.
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We May Have Just Been Visited By An Interstellar Comet
“This object came from outside our solar system.”
— Rob Weryk, postdoctoral researcher at University of Hawaii’s Institute for Astronomy
Diagram of the path of C/2017 U1 PanSTARRS (now A/2017 U1), a possible interstellar comet (or asteroid) spotted on Oct. 18, 2017. (NASA/JPL)
On October 14, 2017, what appears to be a comet (er, make that asteroid…read more below) sped past Earth at a distance of about 15 million miles after swinging around the Sun. It had come within 23.4 million miles of our home star over a month earlier on Sept. 9, and in fact wasn’t spotted by astronomers until Oct. 18—four days after its closest pass by us.
Further observations showed that the approximately 525-foot-wide object (an estimate based on its reflectivity) first approached traveling 16 miles a second from the direction of the constellation Lyra—quite a high angle from the plane of the rest of the Solar System—and is on a hyperbolic trajectory, moving quickly enough both in- and outbound along its course to permanently escape the Sun’s gravity unlike any other comet asteroid ever observed.
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A Comet and the Crescent Moon
Comet Pan-STARRS seen from Alaska on 12 March 2013 © Travis A. Rector
As comet Pan-STARRS heads back out into the depths of the Solar System, it’s become visible to skywatchers in the northern hemisphere (after several weeks of putting on a show in southern skies.) While poor viewing due to weather confounded some over the past few days, many people did get some great views of this cosmic visitor — such as the image above, captured on the night of March 12 by Dr. Travis A. Rector from the Menaker Observatory in Anchorage, Alaska.
“Comet Pan-STARRS is the very faint dot just below the center of the image,” Dr. Rector wrote on his website. “Its tail is pointed towards the upper-left corner. This picture was taken on its greatest elongation from the Sun. Nonetheless it was very hard to see. And nearly impossible to see by the naked eye.”
See a couple more images of Pan-STARRS below:
