UFO Sighting in Horsham, Pennsylvania on July 13th 2011 – Light in sky does 90 degree turn instantly

My sister and I were sitting on the patio talking and having some drinks. We are on a flight path so we see planes pretty regularly. My sister had been making comments about going South when she got up to go inside and make us another drink. I laid my head back on the chair and spotted a moving object very high up in the sky, looking about the same size as surrounding stars. It came across the sky headed West, I said to my sister, "hey Shannon how about that one", she said "nope, its not going south, that's not my ride" and the door closed, suddenly the object made a 90 degree turn and began heading south, disappearing after a few seconds. I yelled to my sister, "hey, it's going south now" before I realized what I had just seen. I was completely stunned and in awe at what I had just witnessed, I am no expert but I KNOW we cannot make 90 degree turns in our aircraft. My sister came back out and we continued looking but did not see it again.