Our Solar System's First Interstellar Asteroid is Named 'Oumuamua'
It was such a new discovery that naming the darn thing became difficult, because there weren't any naming conventions in place for an object like this. It was referred to simply as A/2017 U1 by astronomer Rob Weryk when he first discovered it with the Pan-STARRS telescope in Hawaii, and then it was left alone to fly around at a perpendicular angle to our Sun's orbital plane while it was examined further.
Now, because the asteroid's speed and angle make it very likely that it's about to leave the solar system just as suddenly as it came, the IAU Minor Planet Center is acting fast. Our first visitor from another solar system is now going by the Hawaiian name of 'Oumuamua, deeming it a fitting name because of where on Earth it was first spotted.
The name 'Oumuamua roughly translates to "first scout" or "first messenger".
Planetary Society asteroid hunter snags picture of interstellar visitor ʻOumuamua— Planetary Society (@exploreplanets) November 8, 2017
Asteroid hunters named the first-known interstellar asteroid ʻOumuamua as a nod to its scout-like traits: https://t.co/1txha1ZfOi pic.twitter.com/dJ23ve2Zjj
Beyond that, it also has an official designation of "1I," marking a new standard for naming objects in space: the "I" stands for "interstellar," and is prefaced with a one because it's the very first we've had a chance to see. Here's a quote from the Minor Planet Center's official statement:
It's not clear how much longer 'Oumuamua will remain in our solar system, before its suitable escape velocity launches it free from the Sun's orbit. The Minor Planet Center (a part of the official International Astronomical Union) normally refuses to classify objects which haven't been observed for very long, but an exception was made this time.
And of course, it's impossible to tell where it originally came from, beyond that it's from an entirely different solar system and crossed at least several lightyears, perhaps dozens or hundreds, just to end up in our corner of the Milky Way. The closest possible starting point would be the Proxima Centauri system at 4.2 lightyears away, where dust belts full of asteroids were recently discovered.
NASA (@NASA) October 26, 2017
While it's statistically likely that 'Oumuamua isn't the very first asteroid to cross into our solar system over the past few billion years, our ability to detect these sorts of things is steadily improving. Assuming there have been more before this asteroid, there's sure to be more after, and it may not be long before a "2I" is observed flying through the night sky.
For more information on 1I/'Oumuamua, see here.