The aurora started moving back north again as the magnetosphere appeared to release a burst of energy. These events are referred to as substorms, and they also occur at high latitudes during less disturbed periods where they may last 5-15 minutes during which very active aurora spreads across the sky. This one lasted about half an hour though due to the high activity level, so as you'll see in a few photos I changed to a faster lens with a narrower field of view, allowing me to decrease the exposure time and capture more detail.

Aurora returning

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