e Some persons nevertheless believe that UFOS are extraterrestrial spacecraft, even though no scientifically valid evidence supports that belief. The possibility of extraterrestrial civilizations is not the stumbling block; most scientists grant that intelligent life may well exist elsewhere in the universe. a fully convincing UFO photograph of a craftlike object has yet to be taken however and the scientific method requires that highly speculative explanations should not be adopted unless all of the more ordinary explanations can be ruled outSome persons nevertheless believe that UFOs are extraterrestrial spacecraft, even though no scientifically valid evidence supports that belief. The possibility of extraterrestrial civilizations is not the stumbling block; most scientists grant that intelligent life may well exist elsewhere in the universe. A fully convincing UFO photograph of a craftlike object has yet to be taken, however, and the scientific method requires that highly speculative explanations should not be adopted unless all of the more ordinary explanations can be ruled out