Two slow-moving very low altitude bright white lights about 20 feet apart undergoing rigid motion make a close approach.Time of Day: 1:30 AM to within about 30 minutes either way.Date: Don’t recall exactly. I will say mid-March 2009, but I could be off a month either way. It was mid to late winter or early spring of 2009.My location: Intersection of 108th AVE NE and NE 12th Place at the north edge of McCormick Park on the west side of 108th AVE NE in Bellevue, WA. NE 12th Place is a small dead end side street and not to be confused with NE 12th Street, which is immediately to the south. NE 12th Street is the boundary between urban downtown Bellevue to the south and the suburban/residential area to the north. McCormick Park is a very narrow park that runs on the north side of NE 12th Street between 106th Place NE and 112th Street NE.Weather: Very overcast. No wind. Dark, except for street lighting.Duration of observation: 40 to 45 seconds? Circumstances/description: I was walking my dog at about 1:30 in the morning. I had just crossed NE 12th Street on the west side of 108th AVE NE and had reached the north boundary of McCormick Park which abuts NE 12th Place. I was about to turn west into the park when I looked north up 108th AVE NE and saw two steady (not flashing or strobing) bright white lights about 50 to 60 feet off the ground. These lights were about street width apart (I will say 20 feet -- 108th AVE NE is one lane in each direction there). They were apparently rigidly connected and moving right down the street in my direction. I will put their speed at 20 to 30 miles per hour, 35 tops.I sort of partially hid myself behind a tree next to the street and watched the lights come right down the street toward me (again about 50 to 60 feet up). There was absolutely no visible structure there of any kind, even though I was really squinting and trying to make something out. The lights were all I could see. Furthermore, there was no sound of any kind. When the lights got to about 200 feet up the street, they started to turn to their left (my right). I figure they got within about 150 feet distance of me or less at closest approach – and I still could see nothing but the lights (although they did get dimmer as they started to turn and especially as they started to move away to the northeast). Only at the very closest approach did I hear any kind of sound at all, but I am not sure the sound was coming from what I was looking at. The location I was at is about a half a mile from I-405 and the traffic noise from that distance can be much louder than what I was hearing! at that point. It sounded possibly something like the engine of an ultralight, but exceedingly quiet.As the lights turned they briefly moved to the east perpendicular to 108th AVE NE and finally headed away to the northeast. At some point during this slow-speed maneuver, I did for a fraction of a second get the impression of a dim red light such as you might see in a dark room illuminating part of some possible structure, but it was much to fleeting to make out what I was seeing.Unusual features of object: 1) Silent or virtually silent.2) Invisible, except for two bright white steady lights.3) Moved so slowly a conventional aircraft would have stalled. It could have been a helicopter except for the first two items. I considered, an ultralight, but even an ultralight should have been much louder at closest approach, and even an ultralight would have stalled at that speed – and an invisible ultralight with bright lights 20 feet apart – not a chance. I even had a novel theory that I was seeing something tethered beneath a helicopter flying at a much higher altitude, which I did not see because I was preoccupied with what I was seeing in front of me. My guess: my guess is that I was seeing (er – not seeing) some type of unmanned surveillance aircraft. I am thinking that if a craft did not have to take the weight of a pilot that it would be possible to construct something that would not stall at that speed. Also, there might not be much of a profile to see. There is still the issue that it was VERY quiet, whatever it was, and I still don’t understand why I couldn’t see any type of structure at all. Note: there was one other person in the immediate vicinity who MIGHT also have seen this. Without going into details, he may have had even a much better view than I did, but I do not know who he is, and have no way of contacting him.((NUFORC Note: Witness indicates that date is approximate. PD))