The last few months, after buying a 14mm wide-angle lens, I started getting into star trail photos. I've always been a huge fan of leaving the shutter open. You can see it in some of the first photos I ever took, winter night shots of street lights and snow.
It didn't take long before I started moving lights around in front of the camera, etc. I know it's a basic sentiment since photography is all about time and light, but there is something amazing about how you can see moment pass when you leave the shutter open long enough to capture it. Star trails literally blow my mind as the fact of the earth's rotation is right there in your face. I understand it's science and something we've known about for a long time, but when do you ever actually see it.
Star trail photos put astro physics right in your face. And on top of the science that is going on, they are beautiful images. When you have Polaris in the shot, and the stars streak around that center point, creating that circular clock face in the sky, it just emphasizes the time aspect of it all. Time is passing and I'm standing, alone, usually in a dark place, an invisible shadow straining my eyes to see what the camera is picking up. It's dizzying and fantastic. It's billions of planets and stars racing away from us as we hurtle, spinning, further into the darkness.