For an object that wasn’t discovered until it was already on its way back to wherever it came from, Oumuamua has certainly garnered a lot of publicity. First, of course, it was determined that the cigar-shaped thing was the first known interstellar object to pass through our Solar System. Arguments about what kind of object it is were seemingly settled when astronomers determined it was an asteroid, not a comet, but a strange asteroid with an icy center. That hasn’t pacified the small but vocal group that still believes it’s an abandoned space ship/robotic craft from another civilization. It also didn’t explain why Oumuamua was tumbling nor why it had such an odd surface.
Since it blew by, a team of researchers at Queen’s University Belfast have been studying Oumuamua and think they’ve solved at least some of its mysteries. Led by Dr. Wes Fraser, they analyzed light reflected from the cuts and angles on its surface and, like investigators at the scene of a hit-and-run auto accident, were able to determine that Oumuamua also collided with something and that impact severely damaged its surface and disrupted its rotation as it shoved the planetesimal out of its own solar system and on a path to ours.
“While we don’t know the cause of the tumbling, we predict that it was most likely sent tumbling by an impact with another planetesimal in its system, before it was ejected into interstellar space.”
Their research, published in the journal Nature Astronomy, shows that Oumuamua is spinning “chaotically,” a condition generally caused by a violent impact. Their model indicates this could have occurred billions of years ago and it may take billions more before the shaking and tumbling stops and Oumuamua returns to looking like a tight Nick Foles spiral pass (sorry Tom Brady).
Like the mix of scratched paint, paint from the other car, bare metal and rust that you see after a car accident, the collision may also explain the mysterious variety of colors – from dark red to “dirty snow” — on Oumuamua.
“Most of the surface reflects neutrally but one of its long faces has a large red region. This argues for broad compositional variations, which is unusual for such a small body.”
Knowing all of this will help astronomers in their quest to find more small, dark, chaotic objects with violent pasts like Oumuamua. This is starting to sound like a soap opera, a murder mystery and a sci-fi thriller rolled into one.
Are we SURE Oumuamua isn’t a spaceship?