My 13 year old son and I saw an aircraft flying with two black circles buzzing it.I was in my garden with my three year old son, when we heard an airplane. Upon lookin up at the jet, a 747 I think, I saw two black circles on both sides of the plane, looked like they were flying along side it. The jet was white. Then I saw them move around the plane in very fluid motion. I called for my other son who's 13 to come outside and witness this. The black circles were then back at the sides of the aircraft. Then one went around the nose of the plane, then the other around the black, then back to the sides again. When these circles or spheres were on the side, they were below the wings, looking almost like they were attached to the tip of the wings on the undersides. They continued moving around the plane, then going back to the sides untill the plane was out of view. My son saw a blue marking on the tail of the plane. I didn't notice much about the plane because I was looking at the black balls. Less than a minute later a very fast small jet followed the flight path of the plane. I could hear it but couldn't see it, my son saw it and said that it was the same color as the sky, gray. This jet was considerably louder than the plane with the black circles. I've mailed you a diagram of the circles in relation to the plane.