Last October, astronomers identified a cigar-shaped object hurtling through space that they originally labeled as an asteroid from another star system. However, now it seems that the original identification might have been just a bit off.
After further research, astronomers have determined that the object isn’t an asteroid after all, but rather an interstellar comet. It represents the only interstellar comet of its kind to have been discovered and studied by any space agency.
Comets are usually identified by the long tails that they seem to drag along through the sky. There is no tail visible on Oumuamua, which is why many scientists initially mislabeled the object as an asteroid.
Oumuamua’s trajectory is what ultimately led astronomers to reclassify the object as a comet. Analysis derived by ground telescopes and the Hubble Space Telescope showed that the object was on a trajectory which wasn’t solely driven by the sun and other planet’s gravitational forces—something that is indicative of asteroids. In short, if Oumuamua was an asteroid, it would have slowed down in response to these gravitational forces.
The reason that it hasn’t slowed down is that it is spewing small amounts of gaseous material, which affects the object’s motion—something that’s pretty common with comets. The release of these gases is so small that it wasn’t initially observed when Oumuamua popped up on telescopes.
Some scientists feel that Oumuamua is still an asteroid. Comets are, by nature, made up of dust and ice. Oumuamua seems to have lost so much of its ice that it’s basically just a space rock and according to some, this makes it more of an asteroid than a comet.
Whatever you want to call it, Oumuamua is still a pretty significant find. Many astronomers feel that it’s just the first of many interstellar objects that could make their way into our solar system. Newer, better telescopes should help us find these objects. In turn, we should be able to get a better idea of what planets from other systems are made of and how they form.
Despite Oumuamua’s current 70,000 miles per hour speed, it should hang around in our system for a while longer. It’s expected to pass Neptune in about four years.