Looked out window from highway and saw a line of lights

I looked out the window and saw a line of light in the sky. As we got closer it was several hundred feet or more in the air. The line was not one solid light but about 20 shaped lights in a straight line. Appeared to be letters but I couldn’t make out what they were. The lights did not blink or flicker or change. There was no movement. Once we passed the lights and I was looking back at them but still in close range, they disappeared from the right side to the left. I tried to video and photograph but the light wouldn’t pick up on my phones camera. My husband (driver) also saw the lights.