I live and travel in the Northern Hemisphere. In fact I have yet to travel south of the equator, so my apologies to those of you from the southern half of the planet for my obvious northern bias. I believe those of you in the bottom half of the planet can just substitute the word South for North everywhere and everything should be correct.
- Curvature of the star trails is strongest around the north star. Exposures of about 6 hours will appear to be full circles (24 hours of exposures are actually needed to make complete circles and that is not possible in one night except near the North Pole!).
- The moon will never intervene into the shot because the moon never passes through the northern sky.
- Cassiopeia and Ursa Major (the Big Dipper) are bright constellations that can always be found in the Northern Sky – so there is always some interesting sweep of stars possible. The region immediately around the North Star, however has dimmer stars which may only be captured through long exposures.
- With just a smidgeon of star hopping skill it is easy to find the north star which, weather permitting, is always visible in the night sky.
- The moon sweeps east to west giving long shadows from the right or left of the subject. And when the moon is highest in the sky it can cast strong face light.
- The sun also never appears in the northern sky so it is safe to leave a camera running from before sundown to after sun up. Camera damage can result from a long exposure pointed at the sun.
- Since the moon cannot enter into a northern shot a photo can be made regardless of the moon’s phase and for as long as I choose. For shots toward the East, South or West it is important to know the moon phase and location during the hours of shooting to prevent problems from flare or washout.
- The stars in the north move the slowest through the field of view which allows them to be brighter and reduces inter-exposure gaps in the trails.
- If I know my latitude I know how high to point the camera and be guaranteed to get a circle in the view.
- I do not need to know what constellations will be visible in the direction I will shoot.
- Two major meteor showers (the Perseids and Quadrantids) and 3 periodic meteor showers (the Giacobinids or Draconids, the Ursids and the Andromedids) are well placed in the northern sky.
There are a few detriments to pointing north, however:
- Not every situation lends itself to a view from the south. Just as not every weather condition provides clear views to the north.
- It takes a longer exposure to form a pleasing arc. And if you are like me, you will spend time scheming how to get a complete 360 degree circle (hint, it will take at least 3 nights of shooting over 8 months to get it!)
- To get a circular arc, I must include at least 10 degrees or so above and below the North Star. The altitude of the north celestial pole constrains the choice of lenses to wide angle only except near the equator.
NOTE: Contrary to popular belief, Polaris, the North Star, is not the brightest star in the sky. Sirius is the brightest star. The brightest objects in the night sky are the moon, and the planets Venus, Mars, Jupiter and Saturn. Also while Polaris is quite NEAR to the North Celestial Pole, it’s not exactly there so even Polaris will make a trail.