One thing to be considered is that technology is ever changing. We haven't a clue to how alien life has evolved. They be able to do things far more advanced than any science fiction we have imagined.
I personally have seen a ball of arc white light traveling with the contour of the land in the canyon I lived in after it had traveled a documented long distance then exiting into space over the SF Bay Area at a very high rate of speed. This was seen not just by myself but by many.
Some may claim baloney, but I am certain what I saw and it was and is a technology unknown. A ball of light during the mid-day traveling at subsonic speeds. This was not a plane or missile.
It was clearly a ball that seemed to be an actively flaring arcs of energy surrounding it.
I don't discount the idea in the least that this was not of this planet.
This happened in 1975