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Saturday, Oct 19, 2019

Oumuamua: First interstellar object observed from Earth has an ‘unusual’ cigar shape

The name Oumuamua means a “messenger sent from the distant past to reach out to us”.

science Updated: Nov 21, 2017 15:55 IST
HT Correspondent
HT Correspondent
Hindustan Times, New Delhi
This artist’s impression shows the first interstellar object, named Oumuamua.
This artist’s impression shows the first interstellar object, named Oumuamua. (ESO/M Kornmesser)

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.

The shape of the object, believed to be the first asteroid or comet to be observed by humans, is 10 times as long as it width and has never been seen before.

Scientists who studied images of the object said in a study – published in Nature – that there are “few objects of comparable size in our solar system”. The most elongated objects observed from Earth are no more than three times longer than they are wide, said NASA.

“What we found was a rapidly rotating object, at least the size of a football field, that changed in brightness quite dramatically,” said Karen Meech, the lead author who works at the University of Hawaii’s Institute of Astronomy.

The mystery object, known as A/2017 U1, was discovered in October by a researcher using a sophisticated telescope system at the University of Hawaii that continually scans the universe for such phenomenon.

But the object has another name in Hawaiin language: Oumuamua, meaning a “messenger sent from the distant past to reach out to us”, according to the study.

Oumuamua is also red in colour, which is consistent with the organic-rich surfaces of comets. Researchers said Oumuamua is that only known asteroid or comet that has huge variations in its brightness as it spins on its axis every 7.3 hours.

“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.

Scientists believe our solar system spluttered comets and asteroids while it was forming because of the orbits of large planets. For the same reason, other planetary systems could be throwing out such objects our way, explains CNN.

It could also mean such interstellar objects may give us information about formation of other solar systems, said Zurbuchen.

The mass of Oumuamua, 400 metres in diameter, instantly stood out for scientists because of its extreme orbit, coming from the direction of the constellation Lyra, almost directly above the elliptical plane where the planets and other asteroids orbit the sun.

It crossed under that plane just outside Mercury’s orbit on September 2 before being slung by the sun’s massive gravity into a sharp turn under our solar system. The closest the object came to Earth was about 15 million miles away on October 14.

“It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back,” NASA’s Davide Farnocchia had said in October.

(With Reuters inputs)

First Published: Nov 21, 2017 13:14 IST

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