rating: 0+x

Basic Information

'Oumuamua (the ' is a glottal stop, not an apostrophe) is the first ever detected interstellar object passing through our solar system whose origin was clearly outside our solar system. We almost missed seeing it at all, but an telescope noticed it on October 19 2017, about 40 days after it passed its closest point to our sun, and began traveling out and away from our system.

It's still very mysterious, and shockingly unlike anything we'd discovered previously. Most objects in our solar system are at least vaguely spherical. Even things too small to become rounded by gravity are usually fairly stout and thick. 'Oumuamua is long and thin instead. Measurements are imprecise, but it may be as much as a thousand meters (3,000 feet) long. It's width, however, is probably only about 1/6th to 1/8th its length, making it far more elongated than just about anything else known to be whipping through space. (Just about everything else we've seen in space has its longest dimension rarely be more than 3 times its shortest dimension.) The shape of the light it reflects back at us suggests it is sort of disc-shaped, or maybe cigar-shaped. It's brightness varied by a factor of 10 over time, suggesting it is tumbling (or at least spinning, and not on its major axis). It's also about 10 times more reflective than an asteroid, and is redish in color. As we continued to observe it, it sped up in a way that is not consistent with the gravitational forces it was passing through. This acceleration could be caused by cometary outgassing, but we never observed a cometary tail that you'd expect if that were the cause of the speed-up. It's currently zipping out of our system at roughly 315,800 km/h (about 196,200 mph). The math on this thing is highly atypical, to say the least.

Nobody is really certain what it is, but a number of theories have been suggested. At one time or another, by one expert or another, it was thought to be a:

  • Asteroid - but it's too shiny, and also we realized its trajectory puts it coming from outside our system
  • Comet, Exocomet, or Rogue Comet - but it doesn't have a tail, and unlike a comet it didn't shed mass or size when it sped up
  • A fragment from a disrupted planet - but it's not really the right shape for that
  • A hydrogen iceberg that formed in a giant molecular cloud or stellar nursery - but subsequent math suggests such icebergs wouldn't actually survive traveling through deep space between systems
  • A collection of rocky debris left over from some other object that was destroyed, rather than a single object - but then the debris likely would have generated increased meteor activity after its closest pass by Earth, and that didn't happen
  • An artificial, manufactured, solar sail -yes, that's right, this thing is weird enough that fairly reputable scientists have been willing to publish papers about how it might be alien technology. That's far from the mainstream consensus, but less quackery than you might expect. We've aimed several radio telescopes at it to check for transmissions, just to be safe, and thus far none have been heard.

It's heading away from us now, but several space agencies are considering mounting missions to send probes to catch up with it in the next 5 to 25 years, before it gets too far away for that to be feasible. It's origin, assuming our calculations about its prior trajectory are correct, are likely somewhere in the constellation Lyra (but it's also certainly possible it started somewhere else much further back, and just passed by Vega, a star in the Lyra constellation, roughly 600,000 years ago.) It's currently on a course that will eventually take it towards the constellation Pegasus.

The elongated shape is notably somewhat parallel to Rama from the Arthur C. Clarke story… but that's almost certainly just a coincidence.

The name 'Oumuamua is Hawaiian, and roughly translates as "first distant messenger" or roughly "scout".


2. Scientific American article "6 Strange Facts about the Interstellar Visitor 'Oumuamua"

Game and Story Use

  • 'Oumuamua could be a probe sent by a civilization to assay and investigate the universe.
    • It's a little small to be a generation ship, unless the lifeforms who built it are much smaller than ourselves. But it could have some sort of frozen embryos, a handful of crew in suspended animation, or a astrochicken factory aboard.
    • It may just be collecting data and beaming that back home periodically. If we send a mission to investigate it, or beam a transmission towards it, that might activate a long-dormant sub-routine, or alert an alien empire to our existence. Thankfully, they're probably thousands of years away at top speed.
    • See von neumann probe for more ideas.
    • If a space mission reaches out to 'Oumuamua, they may find it has a core of applied phlebotinum that can be salvaged and taken back to Earth.
    • Or it may be like Pioneer 10/Pioneer 11/Voyager 1/Voyager 2, and bears a message from an alien species eager to make peaceful contact. Perhaps it includes instructions on how to build a subspace ansible or krasnikov tube that allows us to reach out to its point of origin. This is our invitation to sit at the big kids table.
  • It's a peaceful and lethargic Space whale with a glacial metabolism. It had been hibernating as it drifted through deep space, and then sped up a bit after being awoken by solar energy.
    • It may take decades for the space caviar it deposited in the asteroid belt or oort cloud to hatch, but when it does there'll be scores of interstellar tadpoles flitting about near our sun.
  • It's a cast-off tentacle or star-spawn of Azathoth. The acceleration is because it started moving through the fourth-dimensional axis. Don't wake it up!
    • Maybe it was aimed at Yuggoth and missed.
      • Or didn't miss, but rather intentionally came close enough for Mi-Go and Byakhee to fly out and board it.
Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License