I worked at a planetarium for a while. On nights when one of the naked-eye planets were low in the sky, we would get dozens of calls from people either wanting

I worked at a planetarium for a while. On nights when one of the naked-eye planets were low in the sky, we would get dozens of calls from people either wanting to know what they saw, or trying to report a UFO. Often, these reports would claim that the light was flashing and jumping around - an effect from seeing it through a thick layer of atmosphere between the observer and the horizon. Meteor showers or individual meteorites were another rich source of these reports. The variations that can occur here are enormous - see e.g. "Observation of Fireballs" and "Fireballs and Meteorite Falls": https://www.imo.net/observations/fireballs/observations/ https://www.imo.net/observations/fireballs/observations/, https://www.imo.net/observations/fireballs/meteorites/ https://www.imo.net/observations/fireballs/meteorites/ The first link above points out: > "The collision of the meteoroid with atmospheric particles causes ablation, and thereby ionization, of both atmospheric and meteoroid constituents. While most of these excited states exist for about 10^-8 seconds only, there are also some atomic states which may persist for times exceeding several seconds (metastable levels). The emissions from such levels may be visible for variable amounts of time, and are designated as persistent trains (see Baggaley, 1980). They appear bright in the night sky after the meteor itself has disappeared. A large meteoroid entering the atmosphere leaves a substantial amount of material in its wake which is distributed along its trajectory." The kinds of visual effects this can produce are affected by where the trail is relative to the observer - again, looking through more atmosphere tends to create additional effects. And of course, planets and meteors are not the only causes of relatively uncommon visual effects. Clouds, refracted sunlight or moonlight, smoke, jet trails, etc. are all capable of producing effects whose true cause may either not be apparent to a casual observer or even not without careful study by trained observers. In short, large numbers of eyewitnesses to something unexplained is most likely to demonstrate the limitations of untrained observers seeing some unusual but perfectly ordinary phenomenon.