The first interstellar visitor to ever be observed by scientists was seen hurtling through our solar system, and no, it wasn’t an alien, but a quarter-mile-wide hunk of space rock, reports PRI.
Researchers at the University of Hawaii Institute for Astronomy spotted the rock back in October. It was affectionately named “A2017 U1,” and what made it unusual was its speed.
“It has a hyperbolic orbit, which seems to suggest that it came from another star system altogether,”Meenakshi Wadhwa, director of the Center for Meteorite Studies at Arizona State University said, according to PRI. “When you think of all the planets and asteroids and comets that formed within our own solar system, they all have these elliptical orbits that are closed loops, which means that these objects are gravitationally bound to the sun.”
Wadhwa said that in contrast, an object with a hyperbolic orbit “basically indicates that the object is not gravitationally bound to the sun,” according to PRI.
Scientists still don’t know where the rock came from, or how long it has been traveling interstellar space. It crossed the ecliptic plane inside Mercury’s orbit Sept. 2, according to a NASA press release and reported by PRI, and had sunk below Earth’s orbit by Oct. 14. It changed course and headed towards the constellation Pegasus at a fast-pace of 27 miles per second.
Scientists were unable to get samples from the visitor, but spectrum analysis suggests it might look similar to objects that are in our solar system.
Wadhwa told PRI that it is surprising we have not see more interstellar visitors like this because the probability of objects being ejected from other solar systems is high. She hopes to see more in the future.
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