A blinking red light was seen above the tree line in my backyard at about 10:15pm. The light moved from side to side, up and down, diagonally and appeared to move in small circles. It was just underneath where airplanes were flying overhead to take off and land, and would stop moving whenever one passed over. Occasionally the light would flash green or white. At one point, a white flash burst out horizontally from the middle of the red blinking light. It looked as if it was hovering - moving back and forth slowly and steadily - but not changing its relative position to the tree line. This occurred for about 30 minutes and was still there at the time we stopped watching.