NCP star trails illustrating polar alignment
Felt this was a great way to explain polar alignment.
Polar alignment sets the telescope’s “home position” to this stationary point (the “celestial pole”) in the sky – around which the stars appear to move as the Earth rotates.
The right ascension (RA) axis follows this rotation, while the declination (DEC) axis moves you closer to or away from the celestial pole. Once aligned, a target can be tracked using only the RA control (or motor drive).
In the Northern hemisphere the North Celestial Pole (NCP) is located close to Polaris. The South Celestial Pole (SCP) is close to Sigma Octantis in the Southern hemisphere.
Taken with the Canon 6D – 3 minute exposures over around 4 hours of patchy, but very thick, cloud.