What stands out in my mind is the one time I saw the aurora borealis, which isn't often seen in Iowa. I was in bed and happened to glance out the window. There was this red blob before my eyes, and my first thought was that there was something seriously wrong with my eyes. A moment later I realized what I was actually looking at.
Less amazing but still very cool was that comet, some years back, that was prominently visible to the naked eye in the northwest sky. I'm in rural Iowa, which doesn't have huge amounts of light pollution, but the northwest is my darkest sky, which made the comet really stand out.
Growing up, I spent my summers on the Jersey Shore, and in all that time, the only porpoises I ever saw were way out, far beyond the surf. In late summer of 1999, my family rented a house a few doors down from the house we used to own, and there was very large surf coming in from an approaching hurricane. We were sitting out on the deck, watching the waves, and all of a sudden there were these black shapes swimming in the walls of the breaking waves. There were about a dozen porpoises playing in the waves, right out in front of the house.