A star trail is a photograph of the Earth's rotation. The camera sits on a tripod and doesn't move, so as the Earth turns, the stars appear to streak across the sky. Point the camera at the North Star (Polaris) and the trails form circles, because Polaris sits almost directly above the Earth's north pole.
I usually shoot a star trail for an hour or two. The longer you shoot, the longer the trails. Rather than one very long exposure, I take a series of 15 to 30 second exposures, then use software to stack them on top of each other so they add up to one long exposure. It's fairly labor intensive, because I also go through each frame and edit out any airplane or satellite trails. A single star trail can take more than 300 images.
This one was shot in Witting, Texas, at the Evangelical Lutheran Church. It was established in 1884, and services are still held there on the fourth Sunday of every month. We shot it on a bitter cold night (at least for Texas). While the camera was working, the gentleman who looks after the church walked over to see what we were up to. We had a nice conversation, and he ended up handing us the key so we could get out of the cold. That gave us a chance to warm up, and it let us set a light panel inside the church, which is where that orange glow in the windows comes from.
It's still one of my favorite star trail images in my portfolio.