It was big and moved real slow.I was on leave from the US Army, when I was walking along the Agency Road, when I saw lights moving accross the prairie. It was moving a NE to SW direction in front of me, I was standing facing north. AS THE Light crossed in front of me, I noticed that it had a dull or Dark color and that it was "Triangle shape. There was no sound,but it was really big! In fact,it really scared ((deleted)) me!!! As it got close to where I was standing, all the lights went out.The lights were originaly white,like car headlights, or more like aircraft landing lights. I fly,so I know what they look like.