A couple of years ago a police helicopter flew over my neighborhood (a regular occurrence). This night I noticed it was flying around in a consistent circular pattern. I had already thought about the idea of capturing a long exposure of the helicopter before this. So, I grabbed my camera and tripod and quickly took a few of these shots from the porch of my apartment. This has been the most popular picture I’ve posted on Flickr.
https://www.quora.com/What-are-the-most-amazing-photos-you-have-ever-taken