Bright white light races west to east over Portland, OR.Tuesday night, at about 9:45 PM, July 15, 2014, in Southeast Portland, Oregon, as stars and satellites began twinkling, I saw a bright white light race across the sky from west to east. The brightness was like an Iridium flare from a satellite, only it was much larger in radius that a satellite appears to our eyes. I do not think it was a satellite because it was moving so fast and because the glow was so much larger than satellite. I do not think it was an airplane or helicopter either, because the speed was way too fast, there were no other lights besides the consistent glow, and the single white light was larger than any light I've seen on an airplane at night. Also there was no sound. If it had been in aircraft and if it had been flying that fast and presumably low enough to produce a light that large, then I expect I would've heard some noise but there was none. The flight path was west to east over highway 26 in Southeast Portland (Powell Blvd.) Many local aircraft fly this route but none fly it as fast as this: approximately 8 seconds from west horizon to east horizon. I can think of no category to fit the proper description of this light. I do not know what it is, but I'm pretty sure I know what it is not. And that's why I want to share this information here with you. Thank you