Assertion: ufo | /r/HasProperty | optical
Facets:
value: obviously
type: DEGREE
Source sentences:
text: A UFO or unidentified flying object is any object or optical phenomenon observed in the sky which cannot be identified, even after being thoroughly investigated by qualified people.
text: 1) to state that a UFO is an "optical phenomenon" belies many of the proported UFOs that weren't optical.
text: The picture captioned Another UFO from Brazil is obviously an optical phenominon, I think a better, less explained picture should be used.
text: A UFO or unidentified flying object is any object or optical phenomenon observed in the sky which cannot be identified, even after being thoroughly investigated by qualified people.