Research

Lost interstellar asteroid enters our solar system

Lost interstellar asteroid enters our solar system

Astronomers have found around 750,000 of the giant space rocks floating around our solar system.

"This thing is an oddball", said Karen Meech of the University of Hawaii's Institute for Astronomy, who led an worldwide team that studied the interstellar interloper. They published (paywall) their findings on November 20 in a letter to the journal Nature.

A telescope in Hawaii created to spot Near-Earth Objects (NEOs) picked up the asteroid on October 19 as a faint point of light moving across the sky. It initially looked like a typical fast-moving small asteroid, but additional observations over the next couple of days allowed its orbit to be computed fairly accurately.

It is the first observed object from outside our solar system, according to a study published Monday in the journal Nature - and, as the researchers call it, an "oddball".

This artist's illustration shows the first interstellar asteroid, 'Oumuamua.

As regards how 'Oumuamua became so long, Dr Meech explained: "There has been speculation among various team members about this".

Thanks to data obtained by the ESO's Very Large Telescope (VLT) at the Paranal Observatory in Chile, the brightness, color and orbit of this asteroid have been precisely determined.

Unlike other asteroids that have been studied in Near-Earth space and the Solar System at large, 'Oumuamua is unique in that it is not bound by the Sun's gravity. There were more surprises to come. It also spins on its own axis every 7.3 hours. This complex and convoluted shape means the object varies incredibly in brightness.

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The anomalies don't stop there, the asteroid also has a dark red color and lacks any dust around it like many asteroid have.

'Oumuamua is likely made up of rock and possibly metals, and does not hold any ice or water as a comet might, NASA said. Scientists estimate it is about 1,300 feet (400 meters) in length.

Scientists have tracked 'Oumuamua's likely path to have come from the general direction of Vega, a bright star in the Lyra constellation. Traveling at a whopping speed of 95,000 km/hour (59,000 mph), 'Oumuamua would have left the Vega system about 300,000 years ago.

Scientists now know what that interstellar visitor - the asteroid that recently zipped through our solar system from outer space - might look like. The name is Hawaiian and more details are given here. The dotted line shows the light curve expected if 'Oumuamua were an ellipsoid with a 1:10 aspect ratio; the deviations from this line are probably due to irregularities in the object's shape or surface albedo. Note that the character before the O is an okina.

The title of the study is "A brief visit from a red and extremely elongated interstellar asteroid".

Astronomers will continue to make observations of the object before it slips back into darkness. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and by Australia as a strategic partner.

Hence what makes this discovery so significant in the first place. ESO also plays a leading role in promoting and organising cooperation in astronomical research. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope.