Bright object changes color, velocity, altitude and trajectory in East Washington night sky.During the last night of a houseboating vacation on Lake Roosevelt, my wife and I were on the upper deck enjoying the night sky, looking for shooting stars and satellites. All week I had spent my evenings viewing the night sky and seen multiple satellites and shooting stars. At approx. 11:00 PM I notice a very bright object in the south/southwest sky, approximatley 25 degrees above the south horizon. It was the brightest object in the sky by a factor of 4 and I showed it to my wife. It originally had a south to north trajectory and a velocity that should have taken it slightly west of our position and over the north pole. I thought it was just another low orbit satellite. However, at 40 degree above the south horizon it's velocity slowed and it's brightness/color changed from bright white to slightly yellow orange. I had the impression that what ever it was has just bottomed out of a dive, in an arc. It then changed direction and accelerated/fluttered/skipped almost directly away from us getting dimmer as it went into the upper atmosphere. It then turned west after gaining significant altitude and went out of site. I'm not sure what I saw, but it was "not" a plane, satellite, planet, star, etc.((NUFORC Note: Witness has significant technical background, which we suspect makes him a qualified, and discriminating, observer. The witness states that the sighting occurred at 11:00 p.m., which is 2300 hrs.. We have amended the time above. PD))