going south on I95 at mm 320. bright light about the size of 1/2 full moon. just above clouds. (thin curtain of cloud cover at about 20k feet) moving at about 100 mph going south. Lit up the area on the road under it. Got brighter then dimmed and went back to normal, before blinking out. Might have been a large meteor, if not for going so slow. I have never seen anything like it before. I have grown up in central FL and know what a launch looks like.