Minichan

The first-ever detection of an asteroid from beyond the solar system revealed a remarkable object. About 400 meters long and only 40 meters wide, 'Oumuamua's axis ratio of 10:1 makes it the most elongated asteroid ever discovered. The highest axis ratio we see for asteroids in the solar system is only about 3:1. The odd shape is perhaps a clue about when the asteroid was flung from its own star during the formation of that solar system, or perhaps it can tell us something about what happens to space rocks when they fly through interstellar space for millions of years.

And of course there is another remote possibility. Perhaps, just maybe, the object is elongated because it is artificial, the equivalent of a rocket booster or a probe from an advanced extraterrestrial species. Fortunately for the believers, Yuri Milner and Breakthrough Listen are going to point the largest fully-steerable radio telescope in the world, the 100-meter Green Bank Telescope, at the object, which is currently about twice as far away from Earth as the sun.

Avi Loeb, a professor of the Harvard-Smithsonian Center for Astrophysics (CfA) who has written multiple papers on the search for extraterrestrial life, first brought the unique properties of the object to Yuri Milner's attention, suggesting the object could be artificial.

"This is the first interstellar object to be discovered and its axis ratio is so extreme. Therefore when I first learned about it I started wondering whether it might be an artificially-made probe which was sent by an alien civilization," Loeb wrote in notes about the early observation of 'Oumuamua provided to Popular Mechanics. He goes on to point out that the "Keplerian orbit" of the object, meaning its trajectory can be explained with just the gravitational encounter of the sun, makes it unlikely that the object is a controlled space probe. "Most likely, this is just a large rock, but it is worth checking for any radio signal to be sure."