Astronomers may have discovered an asteroid that isn’t part of our Solar system, but is instead a lone traveler, making its long journey through the cosmos.
On October 19, astronomer Robert Weryk spotted what was initially thought to be a comet with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) at the Haleakala Observatory in Hawaii. The object, originally designated C/2017 U1, was found a week later to actually be an asteroid, and re-designated as A/2017 U1. It was also found that its orbital eccentricity — the measure of how elliptical an object’s orbit is — to be the highest ever recorded. A/2017 U1’s dramatically eccentric orbit, combined with its high velocity relative to the Sun, at 26 km/s (16.2 miles per second), means that it was likely never gravitationally bound to our Solar System.
If the asteroid does prove to be from interstellar space, it would make A/2017 U1 the first known example of an interstellar visitor passing through our Solar System. Although the asteroid came from the direction of the star Vega, it’s impossible to tell where it might have originated from.
"It’s coming from very far away, but we can’t actually backtrack how far away it started. It could be that it’s coming from outside the solar system, but it’s really hard to tell," explains Simon Porter, with the Southwest Research Institute.
Astronomers are hoping that observations that will be made over the next few weeks will nail down whether or not our newfound traveler is part of our neighborhood, or is indeed from parts unknown.
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