One year ago a mysterious cigar-shaped object dubbed ‘Oumuamua’ raised a lot of eyebrows among astronomers and science enthusiasts alike when it was discovered traveling through our Solar System at blazing speed. Most scientists agreed that the object was just another asteroid or comet, albeit one with an unusually elongated shape. Others, however, suggested that it could be an artificial structure. A structure possibly created by a long-lost alien civilization. Now, a new research paper by Shmuel Bialy and Abraham Loeb from the Harvard Smithsonian Center for Astrophysics is revisiting this possibility and sparking the debate anew.
The paper isn’t so much about alien civilizations as it is about trying to explain some of Oumuamua’s unusual proprieties. Oumuamua is unique not just because of its shape but also because it’s the first interstellar object ever discovered in our Solar System. Another aspect that intrigued the Harvard researchers was its peculiar acceleration as it was traveling away from the Sun and towards the edge of our Solar System. This type of behavior is common among comets, which can accelerate unpredictably when gasses trapped inside them start to expand and evaporate. Asteroids, on the other hand, are completely barren and are propelled solely by gravity.
Researchers Suggest Oumuamua Could be a Lightsail
What’s interesting about Oumuamua is that it seems to be an asteroid but it’s behaving like a comet. However, the Harvard researchers indicate that the object can’t be a comet. Comets leave behind trails (or ‘tails’) as they evaporate and Oumuamua doesn’t have one. So then why does this asteroid-like object accelerate away from the Sun when it shouldn’t be able to? Well, one explanation could be solar radiation pressure. This type of pressure could theoretically push objects away from the Sun and be responsible for Oumuamua’s acceleration. There’s a catch, though: the object would have to be extremely thin.
“For radiation pressure to be effective, the mass-to-area ratio must be very small,” explains the paper. According to NASA, Oumuamua is about half a mile long (around 800 meters). That means the object would have to be millimeter thin in order for this explanation to work. If true, that opens up an interesting possibility.
Those kinds of dimensions and the possibility that it’s propelled by solar radiation would make Oumuamua a lightsail. This is a possibility the Harvard researchers have seriously taken into consideration. “One possibility is that Oumuamua is a lightsail, floating in interstellar space as a debris from an advanced technological equipment,” says Loeb.
The Second Theory Also Points at Aliens
So is Oumuamua just a floating remnant of an alien civilization? Maybe, maybe not but that possibility is certainly intriguing. It’s also not as outlandish as it may sound. Scientists have been working on creating similar lightsails but on a smaller scale for a number of years now. IKAROS and Breakthrough Starshot are just two examples. In other words, a hypothetical alien civilization just one or two decades more advanced than us should be able to pull off a full-scale functional lightsail. That said, the Harvard scientists have yet another theory about Oumuamua that’s a bit more… out there.
“Alternatively, a more exotic scenario is that Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization,” reads the paper. The researchers admit that scenario is very unlikely, but still plausible in theory.
Oumuamua came out of nowhere in 2017 and disappeared from view before scientists were able to properly analyze it. The object already passed Jupiter’s orbit earlier this year and will pass Saturn as well by January 2019 as it rushes towards the edge of our Solar System. Unfortunately, we’re unlikely to observe it again so we may never know its true origins. Was it an alien probe or just a weirdly-shaped asteroid behaving like a comet? Just like the two Harvard researchers, all we can do now is speculate.