1 green light flying horizontally across the sky, then going down towards the ground at 45 degree angleI was driving south on Hwy. 93 between Whitefish and Kalispell. To my left (east) I saw a green light. It was either circular, or flat on the bottom to make a thimble shape. There was no trail on the light. It flew horizontally across the sky then dropped down below the tree-line. It was going too fast to be an airplane, and the light was also much larger than what would be found on an airplane. It could not have been a meteor because it was going horizontally across the sky, and switched to go down at about a 45 degree angle, and it was too close to the earth to be a meteor. It was not the Northern Lights because there was just this one moving light. There is an airport and military base in the area. It followed a flight path like I'd imagine a missile might.