As government officials and industry experts in Canada and the United States attempt to pinpoint the cause of Thursday's massive power blackout, there is one possibility that has escaped investigation: a close encounter of the third kind. In the days following North America's last major blackout, on Nov. 9, 1965, reports of UFO sightings down the Eastern seaboard convinced some people that visitors from outer space had flicked an interglactic off-switch.The blackout 38 years ago was similar to last week's outage in many ways. The "Great Northeast Blackout" of 1965 began at 5:16 p.m., near the end of a normal workday. The power grid broke up four seconds after the initial disturbance. New York, Ontario, most of New England and parts of New Jersey and Pennsylvania went black within five minutes, leaving 30 million people without electricity for as long as 13 hours. In his 1979 book, UFO Canada, Yurko Bondarchuk writes some believers went so far as to accuse then-prime minister Lester B. Pearson for covering up alien involvement in the 1965 blackout."To shift attention from the UFO explanation, the 'broken relay' story was invented," Mr. Bondarchuk quotes U.S. ufologist Donald Keyhoe as saying. "Since this could be construed as blaming Canada, the prime minister must have been convinced it was best for both countries not to disclose the true situation."The author explained that UFOs can "create sudden power surges in transmission lines as the craft flies overhead." In theory, he wrote, "these power surges could produce blackouts of massive proportions."