Canada, 02:45 AM, Low-pitched hum, Single point of pale blue light, Moved suddenly, Appeared to be ascending, SW to NWI was walking my dog outside of my home at approximately 02:45 AM on the morning of April 1st, 2005 in Gravenhurst Ontario, Canada. It was a clear night, temperature near 5C or 40F and calm winds. For about 3 seconds, while facing NW I heard a muffled yet steady low-pitched humming noise approach me from the SW. I turned and scanned the sky to identify its source. Unable to see anything I returned my sight to the NW and suddenly saw a single point of pale blue light perhaps 35-40 degrees from the horizon at a distance of what I approximate to be 1/2 a mile. The light moved suddenly and appeared to be ascending in the sky as it retreated. It did not blink, change intensity or change in size. I lost sight of it behind a tree but it did not reappear on the other side. My entire experience lasted less than 10 seconds. I was frozen in fear for a few minutes (there were no noticeable effects on my dog's behaviour) as I tried to comprehend how what I had initially heard had traveled from behind me to 1/2 a mile in the opposite direction in only a few seconds without my seeing it overhead. It must have been moving incredibly fast. I live 6 miles from the local airport and it is not uncommon to see aircraft ranging from single prop recreational planes to business jets to air ambulance helicopters or an occasional military aircraft. I know what I saw was not an aircraft.