Bizarre Interstellar Asteroid Is Unlike Any Observed In Solar System
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Bruce Dorminey, Contributor
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Analysis Reveals Elongated, Cigar-Like Shape for First Interstellar Asteroid
Astronomers are still debating the origins of the first confirmed interstellar object to pass through our solar system, now known as 1I/2017 U1 (`Oumuamua). But an international observing team of professional astronomers says that this highly-elongated, 400-meter long asteroid may well have been wandering through the galaxy unattached to any star system for hundreds of millions of years. That is, long before its wholly unexpected encounter with our own solar system.
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.
Discovered only a month ago by astronomers using the Pan-STARRs1 telescope in Hawaii, an international team led by astronomer Karen Meech has made detailed measurements of its properties. “This thing is very strange, with a complex, convoluted shape,” Meech, an astronomer at the University of Hawaii in Manoa, said in a statement.
Among the strangest things about the object is its bizarre, elongated shape, estimated to be some ten times as long as it is wide. Spinning on its axis every 7.3 hours, its extreme brightness variations are unlike any known asteroid or comet from our own solar system.
“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,” Meech said in a statement.
Thus, it apparently is an asteroid and not a comet. Thought to be dense, possibly rocky or with high metal content , the European Southern Observatory (ESO) reports it lacks significant amounts of water or ice, and that its surface is now dark and reddened due to the effects of irradiation from cosmic rays over millions of years.
These properties suggest that ‘Oumuamua is dense, composed of rock and possibly metals, has no water or ice, and that its surface was reddened due to the effects of irradiation from cosmic rays over hundreds of millions of years.
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Although such interstellar objects are thought to visit our solar system about once a year, it’s only been since next generation survey telescopes like Pan-STARRs have come online that astronomers have had a chance to spot them.
`Oumuamua dropped into our solar system from “above” the ecliptic, the plane where most planets and asteroids orbit the sun, and is now skipping away from the solar system, headed back to interstellar space, the University of Wisconsin reported last week. The university noted that even to the largest telescopes, the object appears as a faint, fuzzy spot on a background of stars.
Yet observations are continuing. Thus, astronomers hope to more accurately determine from where it originated and exactly where it’s going next .
Both NASA’s Hubble Space Telescope and NASA’s Spitzer Space Telescope will continue tracking the object this week. As of today, NASA’s Jet Propulsion Lab (JPL) reports that ‘Oumuamua is traveling about 85,700 miles per hour relative to the Sun. JPL says its outbound location is now some 124 million miles from Earth, and some 20 degrees above the plane of the ecliptic — the geometric plane on which our planets orbit the Sun.
As for figuring out where it actually originated?
That may never be possible. But says that preliminary orbital calculations indicate that the object had come from the approximate direction of the bright star Vega, in the northern constellation of Lyra. But Vega was not even near that position an estimated 300,000 years ago when the asteroid passed through that region of the sky. So, where from which star system it ultimately originated will take more calculations and astronomical detective work.
As for where it’s heading?
It will pass Jupiter next may before traveling beyond the orbit of Saturn in January 2019. Once it leaves our solar system, JPL says it will be heading for the constellation of Pegasus.
Ground-based telescopes will continue to track it until mid-December or until it becomes too faint to be detected.
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