All of this is so interesting. 3 interstellar objects since 2017. I don't know the details of our current observing capabilities, but (?) I would think that, as we now view planetary defense as a priority and have more electronic viewing technology to catch faint objects in whole sky surveys, we simply didn't notice them before.

I would expect more every few years in the future.

How interesting!

As far as interstellar alien craft go, I'm not sure what direction it's coming from, but say it was from Alpha Centauri, about 4 light years away. 3I/Atlas is moving about 209,000 km/hr or about 2 to the -4 C. (Not enough for even a good time dilation!) My calculations might be a bit off, but at that, uh, "tremendous" speed, it would take about 1.3 x 10 to the 14th years to get here.

So even if it's just a robotic craft and not accounting for the relative motion of the Alpha Centauri system and our own and the fact that Alpha Centauri doesn't have any habitable planets, Occam's Razor, guys....

But who am I to say? Maybe they decelerated from 0.9 C to check us out.