ESO Observations Reveal More About First Observed Interstellar Asteroid

Artist’s impression of the interstellar asteroid `Oumuamua via ESO

 Recent observations from ESO's Very Large Telescope (VLT) in Chile and other observatories around the world have cast new light on an asteroid that has entered the Solar System from interstellar space. This alien visitor was first sighted by the Pan-STARRS 1 telescope in Hawaii on October 19 of this year.
 Combining images taken using the FORS instrument on the VLT using four different filters with those of other large telescope, the team of astronomers led by Karen Meech of the Institute for Astronomy, Hawaii, found that the asteroid varied dramatically in brightness by a factor of ten as it was rotating upon its axis every 7.3 hours.
 “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. 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," said Meech.
“We are continuing to observe this unique object,” concludes team member Olivier Hainaut, “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!”

Read more about the official press release at: http://www.eso.org/public/news/eso1737/
Or read the full study at: https://www.nature.com/articles/nature25020