First let me give you a little background on myself. I am 75 years old and hold a private pilots license. I live in an area of San Jose where I can observe the landing patterns of commercial flights coming into San Jose from both the north and south. The aircraft coming in from the north (Seattle, Portland) sometime fly very close to my home so am very familiar with their altitude and speed both day and night. Although I am not as close to arriving aircraft coming in from the south (about 5 miles)I am also familiar with their appearance. Aircraft departing from San Jose to the south make a 180 degree turn to the right before continuing south. Aircraft departing to the north (Seattle, Portland) have to make a 360 degree turn to the right in order to gain enough altitude before crossing over the San Francisco area and pass almost directly over my home. I believe at least 10,000 feet. Although my hearing has suffered over the years I am able to hear these aircraft very easily. Last night at approximately 11:20 PM I stepped out on my deck for a smoke and observed a very bright light to the east about 1/3 of the distance between myself and the landing pattern of the flights arriving from the south. It was traveling in a straight line to the SSW at what appeared to be 1000-2000 feet at a speed of between 350-450 knots. If it were higher it would have to have been traveling much faster. There were no flashing red lights or strobes in evidence and made no sound whatsoever. It was completely silent. The observation lasted approximately 20-25 seconds before disappearing to the south. I consider myself an objective person and not prone to jumping to conclusions but I have never observed anything like this before in this area. I have lived at this location for about 5 years.