As a long-time active amateur astronomer, with some formal training in the field, I’ve often been asked if I’ve ever seen a UFO. After all, I have spent thousands of hours staring at the night sky. The answer is yes, at least if you use the “soft”, literal definition of the term: something moving in the sky which you could not identify. Some examples:

1) Featureless moving lights moving in straight lines which can be ruled out as aircraft, meteors or satellites.

Yes, several of them. Possible explanations: illuminated balloons, spacecraft in unusual orbits, airplanes with unauthorized or damaged navigation lights.

2) Ectoplasmic manifestations which can be ruled out as meteorological phenomena or night launches from Cape Canaveral.

Yes, two of them. One was visible through binoculars as a compact, faint glowing mist moving through space, gradually dispersing. The other was a naked-eye, very bright, stationary cloudlike object that rapidly appeared and then gradually faded out, first expanding and then contracting in size before it evaporated into nothingness. Possible explanations: spacecraft doing powered maneuvers in low earth orbit, or dumping fluorescent chemicals (either as a result of an accident or as part of a deliberate but unannounced scientific experiment). Small comets interacting with the upper atmosphere is also a possibility.

I actually published this one, and got a response from an amateur astronomer who had seen something similar to my first sighting while stargazing in Zimbabwe. He mentioned he had corresponded with another amateur in Europe who had seen something similar and had definitely identified it as a Kosmos satellite maneuvering.

3) “Flashers” which can be ruled out as head-on meteors or reflections from satellites because of repetitive occurrences and lack of motion.

A dozen or so, over a period of two nights, in the same part of the sky. About a half-dozen flashes over a twenty minute period on each night. Possible explanation: Reflections off a geostationary satellite or a laser ranging device mounted on a geostationary satellite.

4) Solar transits, which can be ruled as ordinary aircraft.

Two objects crossing the sun’s disk about thirty seconds apart, on the same path, (I was observing through a telescope with a solar filter). The objects were silouhetted against the disk, rapidly moving, and appeared to have a roughly rectangular shape, although it was at the very limit of resolution and they were visible only for a split second, so my impression could be mistaken. Possible explanation: spacecraft maneuvering for a rendezvous, or experimental aircraft at extremely high altitudes.

Any contributions from the rest of you guys?