Bright, moving circular object dims, brightens slightly then disapears in a clear sky.My wife and I were standing in our yard at around 21:20 on 04/17/2009. While looking toward the north my wife noticed a bright "star" like object travelling at a constant rate from west to east. I found the object very quickly after she pointed it out and was able to witness the following.We had been observing the clarity of all of the stars and planets because we have just recently moved from the city to the country and were amazed by the difference in the visible sky. There hasn't been a cloud in the sky all day and there were not any in the sky at the time of the event.At first glance we thought it was an airplane, however it was a solid white color with no blinking and about the same light magnitude of a typical star in the sky. The object continued on its course for less than 10 seconds, dimmed, then brightened for just a split second before disappearing. There was still a visible star to the right of the object when it disappeared. Whatever it was it seemed to follow a "controlled", straight path.My wife and I have never experienced a "UFO" sighting before, ever. I do believe in such objects but the scientist in me wanted to try and disprove what we witnessed. I looked up the orbital paths of the ISS as well as satellites and was unable to find anything with the trajectory that the object followed at the time of the event. We are left to believe that this was indeed our first UFO sighting. We waited for another 20 minutes with both of us watching separate portions of the sky to see if it would return but had no luck.