Objects moved very fast made right angle turns and varied in light intensity. Disappearing and reappearing for approx. 20 minutes.

To whom it may concern: This incident took place during the summer of 1989 (June/July).  It was approx. 22:00 hrs. I was sitting on the side porch of my parents old home talking with a friend when I observed  2 solid white lights in the Eastern sky I found the objects immediately interesting because of their ability to control there light intensity varing from very bright to vanishing completely and reappearing and then moving at a high rate of speed slightly lower in the Eastern sky.  This behavior continued for a few minutes when I decided to get my mother and let her take a look.  During this time we both observed the objects disappear, reappear, vary light intensity, make very fast right angle turns and then return to a previous position.  Rather, interesting we both thought.  After, approx. 20 minutes the object suddenly disappeared.  I'm very knowledgeable in aerodynamics and a plane enthusiest.  I'm niether U.F.O believer or a skeptic I'm just a normal guy reporting what me and my mother witnessed.
Date is approximate.  PD