Disk with 7 red lights moving like a wheel

This object passed directly over me, heading east. It was clearly visible for about one minute. It had 7 red lights in a circular formation. The lights were equally spaced from each other near the edge of the disk and recessed into something solid. The surface of the disk was not visible. I could see the stars in the sky behind the object but I could also clearly see that the lights were recessed in a solid surface. There was no reflection on any surface of the lights. The disk was turned on it's side with the axis (going through the middle of the disk) parallel to the ground.
 The disk moved exactly like a wheel being pushed across the ground because as the disk rotated at the same speed as the object moved forward. It also maintained a constant height above the ground, moving up as it approached and cleared a hill and then down as it went down the other side of the hill.
 The speed of the object was 5 or 6 MPH. The size was at least 60 feet across (from one edge of the disk to the other). The altitude was at least 60 feet. It easily cleared a group of 40-50 foot tall trees.
 I describe it as a disk because that is all I could see of it but it might also have been a cylinder and I could only see one end of it.
 There was absolutely no sound from the object and there was no visible exhaust or disturbance of the air.
 I have seen all manner of man made aircraft in the Seattle area from military helicopters to stealth and B1-B bombers. While I don't know the origin of the object I can say it had none of the chracteristics of any man made craft I have ever seen or heard of.
 My career is in software development.
Witness indicates that the date of the sighting is approximate.  PD