With my lens dialed all the way back to 18 mm and an exposure of almost 29 minutes, here’s my first attempt at star trails.
Here’s the full EXIF info if you’re interested, but more interesting to me was what it looked like untouched. If you scroll down you’ll see the original image looks like broad daylight.
Clouds rolled in during the capture. With a 29 minute exposure, you never know what you’re gonna get.
What are star trails? It’s what the stars look like when you open the shutter of your camera, and leave it that way for a long time. The stars seem to rotate in the sky (it’s really we who rotate), and each star carves a small arc of white light on the picture.
In a capture of 29 minutes, we’d expect each star to travel 2% around the circle, or about 7.25 degrees. In this case, I don’t know when the clouds rolled in and cut them off from view, but probably right at the end of the exposure. The moon was about 94% full, so when it rose, it really lit things up. Thus the unedited photo looks like daylight with dim streaks.