An eminent Harvard astronomer is still spending a lot of his time thinking about our first alien encounter in 2017. That’s when a mysterious object known as ‘Oumuamua passed through the solar system. Scientists have classified ‘Oumuamua variously as an asteroid or a comet, but Avi Loeb, the chair of Harvard’s Department of Astronomy, believes it was really alien — a piece of alien technology we mistook for a naturally occurring space rock.
Astronomers detected ‘Oumuamua in late 2017 as it glided through the solar system. Its speed and trajectory showed incontrovertibly that it came from outside the solar system, but what was it? It didn’t have a coma or “tail” like a comet, but scientists eventually detected a small force nudging ‘Oumuamua away from the sun. We chalked this up to the release of gas from what was probably a very old comet. But was it? According to Loeb, who works as chair of astronomy at Harvard, ‘Oumuamua had too many bizarre properties to be natural. Be believes ‘Oumuamua is truly alien, and we need to take this possibility seriously if we’re going to get a proper look at the next one.
Loeb is set to release a book called Extraterrestrial in the coming weeks that lays out his hypothesis, which does include some compelling arguments. ‘Oumuamua remained undetected until it was already on its way out of the solar system. So, there was no way to intercept or capture high-resolution photographs of the object. However, we know it’s not a typical space rock. Our best estimates say ‘Oumuamua is cigar-shaped and about 100 meters long. As Loeb points out, we’ve never seen a natural object that looks like that. ‘Oumuamua is also highly reflective — about 10 times more so than typical asteroids or comets. That could mean its surface is composed of shiny metal.
What Loeb finds most convincing is the aforementioned force pushing ‘Oumuamua away from the sun. He contends that the out-gassing theory doesn’t sufficiently explain the facts; any jet of evaporating material powerful enough to move ‘Oumuamua should have been visible from Earth. Because we didn’t see ‘Oumuamua until so late in its transit of the solar system, it’s possible we could be wrong about the shape, too. Loeb theorizes ‘Oumuamua could be a disk less than a millimeter thick. Loeb thinks it’s possible ‘Oumuamua was, in fact, some sort of solar sail device that accelerated because of its proximity to the sun.
It’s a fascinating idea, but we’ll probably never know if Loeb is right. ‘Oumuamua is already on its way out of the solar system, and we have no way to catch up. Instead, Loeb wants to encourage scientists to take the possibility seriously and keep an eye out for similar objects so we can gather more data. Astronomers spotted one more alien object after ‘Oumuamua, a comet known as 2I/Borisov. There’s no uncertainty about Borisov’s natural origins, which makes ‘Oumuamua seem that much weirder.