Years ago I read about an actual scientific proposal to look for UFOs. A few people in the UFO scene with scientific backgrounds were trying to crowdfund it.

The idea was to place very sensitive wide angle infrared telescopes at remote locations that are UFO sighting hot spots. Because as long as physics is universal anything flying around, especially like supposed alien craft, must be using a lot of power and rejecting tons of waste heat. They’d have to light up very bright in IR and physics says there’s nothing you can do about it (unless you imagine wild ideas like dumping it into another multiverse slice).

You’d get lots of planes but you could cross reference against public data to remove most of those. And obviously something doing maneuvers that are aerodynamically impossible or would turn a human into strawberry jam is not a plane.

I thought it was a good idea but I don’t think it got funded. It was years ago so the tech might have been very expensive. I bet it would be cheaper now. IMO it would be a good low cost but high payoff experiment.