THE FIRST KNOWN INTERSTELLAR ASTEROID
This oddly elongated visitor to the Solar System was discovered on 19 October 2017 by Rob Weryk and Marco Micheli at the Institute for Astronomy in Honolulu, Hawaii, using observations from the Very Large telescope in Chile.
The asteroid's name 'Oumuamua' means 'a messenger from afar arriving first'.
The asteroid's speed and trajectory indicate it may have originated in a planetary system around another star. Oumuamua's observed properties suggest that it is a dense object, comprised 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 long periods of time. It could have been wandering through the Milky Way, unattached to any star system for hundreds of millions of years before reaching our Solar System.
Searches across four different radio frequency bands for anything that might resemble a signal resulting from alien technology have so far drawn a blank.
Professor Alan Fitzsimmons of Queen's University Belfast and colleagues have carried out measurements suggesting Oumuamua may have an insulating, carbon-rich layer on the outside, due to long exposure to cosmic rays, that could have shielded an icy interior from its encounter with the Sun.