Look to the skies above and you might see any number of craft overhead. Aeroplanes, helicopters, drones, UFOs… there’s all sorts. And if you have a clear line of sight (LoS) to a patch of sky, then with some not very expensive kit you can find out a little about your local air traffic, making those UFOs a little more identifiable.
Most air jurisdictions require aircraft using them to send periodic ADS-B (Automatic Dependent Surveillance-Broadcast) data. In the US the FAA is moving away from ground navigational aids (such as radar) in favour of ADS-B, because it’s safer, cheaper and provides more information. It’s also much more feasible
