kleinbl00 has me reading Avi Loeb's book "Extraterrestrial", which is about the object we named Oumuamua that zipped through our solar system a few years ago on a very weird trajectory and left a lot of questions in its wake.
Loeb's contention is that it was a manufactured thing of extraterrestrial origin. Either a solar sail or beacon/buoy from another civilization somewhere 'out there'. (I haven't finished the book yet, so maybe he postulates the exact location. Dunno. Immaterial to my comment anyway...)
Or, as KB says, IT'S RAMA.
I like the thought that it was a stationary buoy used by a space-faring people, and our Solar System happened to run into it, rather than it running into us.
Now here is a galactic fact to keep in your mind: It takes about 250 million years for our solar system to make one circuit around our galaxy.
Add to that the fact that the Permian-Triassic extinction killed off all but 5% of living things on Earth... about 250 million years ago. And it was probably an asteroid, they are thinking now, because the extinction event was so abrupt. (8,000-100,000 years to wipe everything out.)
Here's my thought: I wonder if there is a debris field in interstellar space that our galaxy is rotating through, and when our Earth enters this 'bad neighborhood' every 250 million years, bad things happen to our planet...?
I don't know if Oumuamua could be a celestial "Warning: Bridge Out!" sign, warning those entering this region that the roads get bad from here on in... or even what its purpose might be/have been.
But these two separate things I know about are crossing each other in my life right now, and they are the kind of big cosmological questions I like to think about on warm evenings with a drink or two in my belly....
... anyone have any thoughts on either of these?