very bright light with tail, traveled slowly, about 5,000 feet in the air, was NOT comet.Around July, 2007, It was a very calm day without any kind of cloud insight. The sun was already pre-setting. Me, my mother, and sister were outside enjoying the afternoon, we live on a lake and we had a long dock to go with it. My mother and sister, were in front of the house as I started jogging down a hill towards my dock. I happened to look in the sky and I saw a very bright circular light with a tail. Now I know what a comet looks like, and this was something I never seen before, I stopped dead in my tracks and gazed at the light. It started to go out of my view, I ran to the end of my dock and it was still their, this light looked as if traveled very slowly as if a airplane high off the ground and it made no noise. But I assumed the light was about 5,000 ft. in the air, the light looked like it had a high force of light, almost like a car light 150 yards away in the dark. I yelled at my family to come and see this but as soon as I turned around the light vanished and was nowhere to be seen.