Pole Star
Pole Star, photo by Harold Davis. View this image larger.
This is the last of a sequence of twelve photos of the wrecked Point Reyes trawler near Inverness. I took these photos the other night over the course of a couple of hours. The sequence started with The Long and the Short, and included Star Trawler. Like Star Trawler, this last capture in the series is a 1,204 second (20 minute) exposure.
As I was taking this photo, I was interested in the reflection of the boat in the water. I’ll admit I was pretty bored with all the waiting around during the long exposures and the in-camera noise processing, so I augmented the reflection with a little discreet light painting on the hull with my headlamp.
I also angled my camera so that it was facing due north and the Pole Star. The Pole Star, also called Polaris or the North Star, is almost stationary in this photo while all the other stars trail around it. This is because the Pole Star lies nearly in a direct line with the axis of the Earth’s rotation “above” the North Pole.
It has been rudimentary night-time navigation for thousands of years in the nothern hemisphere to determine north using the Pole Star (and is still useful if you are lost in the wilderness at night without a GPS or compass).
To determine north, first find the Big Dipper. Next, locate the “cup” part of the dipper so you can draw a mental line extending from the star Merak and extending beyond the star Dubhe (you’ll find a diagram in the Wikipedia article). The extended line will point at the bright Pole Star (it’s about five times as far from Dubhe as Merak and Dubhe are apart). Draw a line from the Pole Star to the earth, and you’ve fairly accurately found north.
This explains why I was excited when I spotted the Big Dipper pointing to the Pole Star directly above the wreck of the Point Reyes. I was hoping to capture the stars whirling around the single still point of Polaris above the boat.
[Nikon D300, 12-24mm zoom lens at 13mm (19.5mm in 35mm terms), 1,204 seconds at f/22 and ISO 100, tripod mounted.]
August 23rd, 2008 at 11:01 am
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