Scientists are still scratching their heads about an interstellar object that came into our solar system in 2017, but one thing is now clear: The cigar-shaped object astronomers named 'Oumuamua was perfectly natural, reports Space.com. That might disappoint those who theorized that 'Oumuamua, the first interstellar visitor we know about, could have been some kind of alien spacecraft. "There is a whole host of natural phenomena that could explain it," says Matthew Knight of the University of Maryland, co-author of a new study in the journal Nature Astronomy. For example, one model "shows that comet-like outgassing can explain 'Oumuamua's nongravitational acceleration and spin at the same time," study co-author Sean Raymond writes on his blog.
Raymond also disputes the claim that 'Oumuamua's orbit, which brought it nearer to Earth than any other planet, was a course specifically plotted to bring it within sight of humans. In fact, it's possible 'Oumuamua is just the first of many similar, faint objects to be spotted. "We may start seeing a new object every year. That's when we'll start to know whether 'Oumuamua is weird, or common," Knight says, per Space.com. "If we find 10-20 of these things and 'Oumuamua still looks unusual, we'll have to reexamine our explanations." Meanwhile, CNET notes that the European Space Agency plans to launch spacecraft capable of visiting an interstellar object like 'Oumuamua by 2028. (A European team thinks it was a comet.)