Interstellar asteroid is unlike anything we've ever seen
Meteorologist/Science Writer
Monday, November 20, 2017, 7:36 PM - The very first interstellar visitor ever detected has turned out to be very strange and unique, unlike anything we've ever seen so far in our own solar system.
A few weeks ago, we heard about the "interstellar visitor" that was passing through out solar system. This 400-metre-long asteroid, first spotted by Canadian astronomer Robert Weryk, had likely travelled for millions of years from another star system to reach us, and was only spending a short time here before it swung back out of the solar system to another interstellar destination.
"What a fascinating discovery this is!" Paul Chodas, manager of the Center for Near-Earth Object Studies at NASA's Jet Propulsion Laboratory, said in a statement. "It's a strange visitor from a faraway star system, shaped like nothing we've ever seen in our own solar system neighborhood."
This diagram shows asteroid 'Oumuamua's path through the solar system. An analysis of its path shows that it is coming from the direction of where the star Vega is now, although Vega would not have been at that location millions of years ago. Now that it is leaving, it is headed for the constellation Pegasus. Credit: ESO/K. Meech et al.
A new report, written using observations made using the European Southern Observatory's Very Large Telescope, is now providing even more information about this asteroid, which the International Astronomical Union has now named 1I/2017 U1 ('Oumuamua).
The combination of VLT images, using a special instrument known as FORS, with those from other telescopes has shown that the asteroid tumbles through space, rotating about its axis roughly every 7 hours and 20 minutes, and as it does so, its brightness changes by a factor of ten.
Watch below as Asteroid 'Oumuamua tumbles through space.
"This unusually large variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape," Karen Meech, from Hawaii's Institute for Astronomy, who is the lead author of the study published in Nature, said in an ESO statement. "We also found that it has a dark red colour, similar to objects in the outer Solar System, and confirmed that it is completely inert, without the faintest hint of dust around it."
According to the ESO:
These properties suggest that `Oumuamua is dense, possibly rocky or with high metal content, 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.
'Oumuamua (pronounced oh MOO-uh MOO-uh) may be on its way out of our solar system, at a speed of 138,000 km per hour, but telescopes on the ground continue to watch it, and both the Hubble and Spitzer space telescopes are tracking it this week. Observations will continue until it becomes too faint to see, even with our most powerful telescopes. NASA estimates that this will happen sometime after mid-December.
This artist's illustration shows the asteroid's high-elongated shape. Anyone read the sci-fi novel 'Rendezvous with Rama'? Credit: ESO/M. Kornmesser
"We are continuing to observe this unique object," said Olivier Hainaut, a member of the study group from the ESO in Germany, "and we hope to more accurately pin down where it came from and where it is going next on its tour of the galaxy. And now that we have found the first interstellar rock, we are getting ready for the next ones!"
