A recently revealed British Ministry of Defence report on UFOs claims that "no evidence exists to suggest that the phenomena seen are hostile or under any type of control, other than that of natural physical forces." The report named meteor activity, and other events related to "physical, electrical and magnetic phenomena in the atmosphere, mesosphere and ionosphere" as the source of unusual aerial sightings. Read more at BBC News(1).

1. http://news.bbc.co.uk/2/hi/uk_news/4981720.stm