What if they from a higher dimension, and the craft we see is just the 3D observation part of the ship, like a microscope looking at a 2D slide.
Discussion
If they learned to jump dimensions then I'd think time would also be a factor. A device that could peer into the next dimension and collect data of environment in time would probably be helpful prior to the jump.
Could be. It's really probably unlikely they came from a distant star with what we currently know of physics.
The amount of power it would take to accelerate and decelerate to speeds close to light would be massive and any small debris (of which there is a lot of in space) would blow the craft up on impact.
And you also have radiation to deal with having no real atmosphere.
Many problems to solve. Might be easier to travel to a sideways dimension than to another solar system.
And even if you do travel to other stars, you could do it in one lifetime but for everyone else thousands of years would have passed.