Most of astrophotography is long exposure photos (except photos of sun and some other exception). During long exposure time a lot of can happen. Tripod may move, focus of camera may change, etc. Sometimes you even not remember what happen and only see some strange result on photo. I started astrophotography in middle school with such weird photos. Photos had UFO, which I did not saw by naked eye. Probably it was reflection of car light but maybe not.
There is very close popular photo technic - Intentional Camera Movement. But I am talking about Unintentional Camera Movement. This is one of the photos from adventures in Bolivia. Photo was done in Salar de Uyuni. Interesting effect – looks like camera reached warp speed. No Idea how it happened, probably changed zoom.
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Unintentional Camera Movement Astrophotography - Warp Speed |
And this is one more example
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Unintentional Camera Movement Astrophotography - Meteor Shower |