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A mysterious cigar-shaped object that astronomers spotted in the solar system last year could be an artifact of an extraterrestrial civilization sent to explore the vicinity of the Earth, two Harvard astronomers postulated.
The researchers said the non-gravitational acceleration displayed by the object called Oumuamua could be explained by the effect of solar radiation pressure on a light sail, a sail pushed towards the sea. Before, because it reflects the light of the sun.
A group of Hawaiian astronomers first sighted the object on October 19 and noticed in a few days its unusual features – a dark red hue and a very elongated shape of about 800 m from long – as well as a trajectory indicating an origin outside the solar system. "Oumuamua" means "scout" in Hawaiian.
Groups of astronomers from Europe and America who watched the rapidly fading object move away from the Sun wondered whether it was an asteroid or a comet.
Abraham Loeb, professor and president in astronomy, and Shmuel Bialy, postdoctoral researcher at the Harvard Smithsonian Center for Astrophysics have in an article submitted to The letters of the astrophysical journal now brought a new angle to this discourse.
"Our article suggests that the first evidence of extraterrestrial technology could be passed by the Earth last year," said Loeb, also director of Harvard's Institute of Theory and Computing, e-mail from the Telegraph.
Scientists from Europe, Israel and the United States had, in June of this year, based on multiple observations, reported an acceleration of Oumuamua impossible to explain by the gravitational effects of the Sun or other objects of the solar system.
In an article published in the journal Nature, scientists attributed this acceleration to gas emissions that occur when the ice of a comet vaporizes under the effect of heating by the sun.
But no cometary tail was seen around Oumuamua. Astronomers have also not observed variations in its spin that a gaseous release similar to that of a comet would have produced.
Loeb and Bialy proposed that the non gravitational acceleration of Oumuamua was produced by a light sail. They pointed out that sails of light of similar dimensions had already been designed and built by our own civilization. In 2010, Japanese engineers launched a light sail called Ikaros.
Harvard astronomer's journal shows that a light sail with a thickness of only 0.3 to 0.9 mm could survive a long journey into interstellar space, free of probable collisions with atoms or dust particles .
"One possibility is that Oumuamua is a light sail floating in interstellar space as a debris of advanced technological equipment," they wrote in their article, citing previous studies suggesting Use of bright sails for interstellar travel.
"Alternatively, a more exotic scenario is that Oumuamua could be a fully operational probe, intentionally sent to the vicinity of the Earth by an extraterrestrial civilization," they said.
Astronomers said that it was assumed that Oumuamua had an elongated, invisible shape in no known asteroid or comet. The information on its shape comes from the variation of sunlight when it turns, said Loeb.
Even a thin sheet folded like an umbrella could appear at a distance similar to that of a rotating cigar depending on the variation of sunlight, he said.
Bialy stated that current observations do not rule out a crepe-like geometry. Studies looking more closely at the light signals suggest that Oumuamua could be very elongated, cigar-shaped or pancake-shaped.
"What is clear is that it can not have an almost spherical shape – like normal rocks that we know," he said.
Loeb said that the mystery of the origin of Oumuamua remains. "It is not clear if it is an old or functional technological debris. The radio observatories have detected no transmission (with instruments capable of detecting transmissions) at a power level greater than one-tenth of a single cell phone, "he said.
Astronomers have suggested to intensify the surveillance of similar objects. "Since it is too late to image Oumuamua with existing telescopes or to hunt it with chemical rockets," they wrote, "its origin and likely properties could only be deciphered by searching for others." objects of this type in the future ".
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