The first interstellar object spotted racing through our Solar System last month has an "unusual" elongated, cigar shape and is red in colour, astronomers say. Speed was vital as 'Oumuamua was rapidly fading as it headed away from the Sun and past the Earth's orbit, on its way out of the Solar System. It is surrounded by the trails of faint stars that are smeared as the telescopes tracked the moving asteroid.
None of the approximately 750,000 known asteroids and comets is thought to have originated outside our Solar System, but formation models suggest that orbital migration of the giant planets ejected a large fraction of the original planetesimals into interstellar space.
"For decades we have theorised that such type of interstellar objects is out there, and now -we have direct evidence that they exist", stated by Thomas Zurbuchen, associate administrator of NASA Science Mission in Washington. Observations from ESO's Very Large Telescope in Chile and other observatories around the world show that this unique object was traveling through space for millions of years before its chance encounter with our star system. Urgency for viewing from ground-based telescopes was vital to get the best data. Meanwhile, the VLT's FORS instrument with four different filters allowed a team of astronomers, led by Karen Meech of the Institute for Astronomy in Hawaii, to discover that its brightness varied by a factor of 10. The most elongated objects we have seen to date are no more than three times longer than they are wide.
They also believe that the object, which is dark - absorbing 96% of the light that hits it - could contain abundant hydrocarbons, the building blocks for life that many scientists believe first arrived on Earth from asteroids. It's incredibly dense, likely made up of a rocky or high metal content, though it has no water or ice.
It is travelling about 138,000km per hour (38.3km per second) relative to the Sun, and is now about 200 million km from Earth - the distance between Mars and Jupiter. The object passed Mars's orbit around November 1 and will pass Jupiter's orbit in May of 2018. Estimates range from one to ten per year, and with new, more powerful telescopes, astronomers hope to see more of them in the near future. Since asteroids merge during the process of planet emergence, this mysterious object can tell us many things about the generation of planets around its hidden parent star. The name was chosen by Hawaiian language experts, and it means "messenger sent from the distant past to reach out to us".