I was driving on hwy 503, just north of battle ground wa. headed south and i noticed a bright light flying through the sky ahead of me. i slowed down to 40 mph so i could keep my eyes on the road as well as up in the sky to tactfully track it's path. i was not sure if it was a bright reflection on the surface of it or an actual light itself, until i noticed the shadow pattern on it's surface, away from the reflection/light was showing a grey sphere type of thing, it indicated it could have a tapered outer rim based upon the shadow pattern, but i am not sure. it flew for about 5 seconds or more and vanished. i took note that the sun was to the right of it, if it was a reflection, it should have been on the right side, not the left, and the shadow should have been on the left side, not the right, being an artist i know light and shadow alignment and positioning. i think the light it was emitting overpowered the suns light, thus created it's own shadow on the bottom of what ever it was, overriding the natural sunlight. it was flying about 400mph or less and was about a mile south of me, and about 500 -700 feet in altitude. it did not change direction during it's flight as well. i can provide a sketch if need be. adding for what it's worth additional details that may or may not have any relevance. i woke today with a nose bleed, something i've rarely experienced in my life, and for some reason i knew without seeing was what coming out of my nose, what it was.