Opalescent , round (40 ft - 12 meters in diameter) flying object spotted in Seattle-Northgate area

My spouse and I were sitting outside in our yard watching (and waiting for) the meteor shower.  At the same time I was on the phone talking to a friend whom lives in Las Vegas.  During the time we were outside, we spotted the occaisional meteor.  I also saw a satillite.  We were facing North-North East.  From the North an opalescent, round object, approxmiately 40 feet (12 meters)in diameter appeared from the North heading in a Southernly direction.  The sky was cloud free...in consideraton of seeing other aircraft in the sky, I would say it was approxmiately 2000 feet in the air.  At first I thought it was a large helium, party balloon.  After looking at it more closely, I realised it was a round, solid object.  It traveled fairly fast...I would say it was traveling faster than a jet approaching SEATAC. (We live one block from Aurora Avenue (Hwy.99) between a major avenue and a cemetery.)  At the same time I was telling my friend on the phone what I was seeing.  She too was fascinated by what I was telling her and I gave her a "play-by-play" account while I was looking at the object. I watched it until I could no longer see it in the distance.  I felt frightened and fascinated at the same time.  Also, it had a fuzzy glow about it and no sound seemed to be coming from it.  We were very excited to see it and I wanted it to fly more around my area so I could enjoy the moment more.  Tonight, I am feeling very lucky to have seen such a thing.