Bright white round light with wide fanned tail flying slowly north then suddenly disappearingWas standing in parking lot of the Clark County Fairgrounds, some miles north of Vancouver, WA. Looked up at sky (toward the south and facing general area where Portland airport might be) and saw a very large bright, round white light emitting a very wide, fan shaped vapor or trail behind it. Object was moving north, toward me, straight across the night sky (which was very clear, no clouds)at a slow, steady speed. It was about as high in sky as a major airliner would be having just left Portland airport heading north. I pointed it out to a friend I was with, and we both watched the object for several minutes, which we originally thought was a plane with its headlights facing us. We both found it very strange that this object, if it was a plane, had such a strange wide fanned out trail or tail behind it - almost like a comet. All of a sudden the bright light just disappeared, followed by the disappearance of the fanned out tail/trail.Very strange. When I told my husband he said it sounded like a piece of space junk disintegrating in the atomosphere. I would be curious to find out if anyone else saw this as it was very noticeable and still early in the evening where a lot of traffic on roads would be aware of it. Could you please inform me of your findings on this object.((Vandenberg rocket launch. PD))