As 2019 came to a close, news reports spread about nearly two dozen “mysterious” drones sighted in the night skies over rural Colorado and Nebraska. Despite the (presumed) drones apparently operating legally under Federal Aviation Administration (FAA) regulations (and not, for example, at a high altitude or near an airport or government buildings) authorities launched investigations. Concerned—and/or annoyed—residents asked if it was legal to shoot the drones down and were told it was not a good idea; it is considered an aircraft and someone else’s property. Still, people were understandably unnerved.

Of course, most drones are, strictly speaking, “unidentified” unless launched in a public place, such as a park, where someone is seen watching or controlling the drone. Otherwise, they’re just anonymous mechanical craft hovering or flying overhead, devoid of clear identifying marks. Various explanations have been offered, ranging from the malicious to the mundane, but so far no companies or individuals have come forward to claim responsibility for the reports.

A few videos have circulated of the lights, none of which actually reflect the most dramatic descriptions. Instead of dozens of huge drones with “six-foot wingspans” flying in formation (as some have reported), they merely show one to a few lights somewhere in the sky. Reliably estimating size, speed, and distance of lights or objects in the sky is extremely difficult under the best of circumstances; doing so at night is even more fraught. Social and psychological factors are certainly at play as well, as the history of so-called UFO flaps teaches us. When people’s attention is drawn to the sky, especially in service of looking for anything potentially strange or unidentified, they are likely to see what they’re looking for—whether it exists or not. It’s entirely possible that identical drone flights occurred in other places around the same time but went unnoticed.

This is not to suggest that people are imagining the lights; there are indeed many lights in the night sky, including those from satellites, stars, planets, planes, meteors, the International Space Station, military flares (the provable source of several notable UFO sightings), helicopters, and, of course, drones.

So what are people seeing? Many probably are drones, which after all are widely used by journalists, photographers, police, railways, the National Oceanic and Atmospheric Administration (NOAA), surveyors, Amazon.com, the military, and so on—and are increasingly popular with hobbyists. There is unlikely to be a single blanket explanation for all the reports, which were seen in different places by different people at different times. The most likely explanation is that people are seeing a variety of things, all being lumped together by the news media and mystery mongers, into a terribly mysterious—and possibly nefarious—event.