Scientists deliver verdict on visitor from interstellar space

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  Last updated January 11, 2018 at 10:46 am


NASA scientists have detailed their observations of the asteroid that is streaking through the solar system –the first confirmed object that has come from another star 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 Hawaii. Credits: European Southern Observatory/M. Kornmesser

The asteroid, that has been named ‘Oumuamua, is rocky and cigar-shaped, about 400 metres long and 40 metres wide.

Its speed varies but it is currently travelling at about 138,000 km/h relative to the Sun. It is about 200 million kilometres from Earth – the distance between Mars and Jupiter. ‘Oumuamua passed Mars’s orbit on 1 November and will pass Jupiter’s orbit in May next year. It will travel beyond Saturn’s orbit in January 2019 and leave our solar system in the direction of the constellation Pegasus.

Its origins are hard to determine, however. While it appears to have come from the approximate direction of the bright star Vega, in the northern constellation of Lyra, it has taken so long to travel here, even at its vast speed, that Vega was not near that position when the asteroid was there about 300,000 years ago.

Scientists suggest it has been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years.

“For decades we’ve theorized that such interstellar objects are out there, and now – for the first time – we have direct evidence they exist,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate in Washington.

“This history-making discovery is opening a new window to study formation of solar systems beyond our own.”

The asteroid was discovered 19 October by the University of Hawaii’s Pan-STARRS1 (the Panoramic Survey Telescope and Rapid Response System) telescope, funded by NASA’s Near-Earth Object Observations (NEOO) Program, which finds and tracks asteroids and comets in Earth’s neighborhood. ‘Oumuamua (pronounced oh MOO-uh MOO-uh), is a Hawaiian word meaning “a messenger from afar arriving first”.

Astronomers believe that about interstellar asteroids similar to ‘Oumuamua are not uncommon in the inner solar system, but they are faint and hard to spot. It is only recently that survey telescopes, such as Pan-STARRS, are powerful enough to have a chance to discover them.

About the Author

Bill Condie
Bill is former Head of Publishing at the Royal Institution of Australia. Previously he was Publisher of the popular science magazine, Cosmos, based in Melbourne, Australia. Bill has been a journalist for more than 30 years and his work has been published in Cosmos magazine, The Guardian, The Observer, The Times, The Daily Telegraph and the London Evening Standard.