The mysterious cigar-shaped object astronomers noticed in the solar system last year may be an artifact from a cosmic civilization sent to investigate the neighborhood of the Earth, postulated by two astronomers from Harvard.
Researchers have found that the non-gravitational acceleration displayed by an object called Oumuamua can be explained by the influence of solar pressure on the light-sail, the sail pushed forward because it reflects sunlight.
A group of Hawaii astronomers first noticed the object on October 19 last year and noticed in a few days its unusual features – a dark red tint and a very elongated shape, about 800 m in length – and a trajectory that pointed to origin outside the Solar System. "Oumuamua" means "scout" in Hawaiian.
Groups of astronomers in Europe and America that observed the rapidly disappearing object as they moved away from the Sun, discussed whether it was an asteroid or a comet.
Abraham Loeb, professor and chairman of astronomy, and Szmuel Bialy, assistant professor at the Harvard Smithsonian Center for Astrophysics, in the article Astrophysical Journal Letters now he brought a new point to this discourse.
"Our publication suggests that the first evidence for the existence of extraterrestrial technology could have just passed last year on Earth," said Loeb, who is also the director of the Harvard Institute of Theory and Computation, via email in The Telegraph.
Researchers from Europe, Israel and the USA in June this year, based on many observations, reported the acceleration of Oumuamua, which could not be explained by the gravitational effects of the Sun or other objects in the Solar System.
In an article published in the journal Nature, the scientists attributed the acceleration of gas emissions that occur when the ice on the comet evaporates as a result of heating by the sun.
But in Oumuamua you can not see the comet tail. Neither astronomers observed changes in its spin that would create a comet-like degassing.
Loeb and White proposed that the non-gravitational acceleration of Oumuamua could be produced by a light sail. They emphasized that light sails of similar dimensions were already designed and built by our own civilization. In 2010, Japanese engineers launched a light sail called Ikaros.
The work of Harvard astronomers shows that a light sail of only 0.3 mm to 0.9 mm can survive a long journey in the interstellar space, without prejudice to possible collisions with atoms or dust particles.
"One of the possibilities is that Oumuamua is a light sail floating in the interstellar space, like the remains of technologically advanced equipment," they wrote in their article, citing how previous studies proposed light sails for interstellar travel.
"Alternatively, a more exotic scenario is that Oumuamua can be a fully functional probe sent intentionally to the Earth's surroundings by a foreign civilization," they said.
Astronomers have said that Oumuamua has been derived to have an elongated shape, unobserved in any known asteroid or comet. The information about its shape results from the variety of light reflected during the spin, said Loeb.
Even a thin sheet folded as an umbrella may seem from a distance similar to a rotating cigar based on the variability of sunlight, he said.
White said that the current observations did not rule out a geometry similar to pancake. Studies that examine light signals in more detail suggest that Oumuamua can be very elongated in the shape of a pancake-shaped cigar.
"It is obvious that it can not have a shape that is almost spherical – like the normal rocks we know," he said.
Loeb said that the secret of Oumuamua's origin remains. "It is not clear whether it can be a non-existent technological waste or is it functional." Radio observatories did not detect any transmission from it (with instruments capable of detecting transmission) at a power level higher than one tenth of one mobile phone – he said.
Astronomers suggest increased supervision over similar objects. "Because it is too late to visualize Oumuamua using existing telescopes or chase them with chemical rockets," they wrote, "its probable origin and properties could be decoded by searching for other objects of this type in the future."