Subject Matter for Star Trails

Where and When to Photograph

While it’s implied at the beginning of this article, the best opportunity for star trail photography is at locations where light pollution is minimized. Articles often recommend anywhere from 30-150 miles away from major cities. But cities will radically differ depending on their geographic location and the amount of outlying sprawl. In general, if you’re able to see a very dark sky, lots of stars, and ideally, the Milky Way, then you’re in a good place. You can even use distant city lights to your advantage — I’ve seen some lovely star trail photography from Death Valley that creatively captures light pollution from Las Vegas over 100 miles away.

Star Trails over the Three Patriarchs, Zion National Park
Star Trails over the Three Patriarchs, Zion National Park. This image utilized a rising near-full moon to illuminate the foreground.

While the "when" is subjective there’s one key factor to consider, namely, nighttime flying objects. For a few hours after sunset, the sky is filled with planes, sunlit satellites and occasional non-identifiable objects (think animals, not aliens). To minimize their intrusion, the rule of thumb is the later in the evening the better. Domestic planes are generally grounded after 11 pm and satellites no longer reflect sunlight. In my experience, some objects will still end up in your photo but the later you make the photograph, the fewer issues you’ll have to deal with in post-processing. My most successful captures are early morning ones, starting between 3-4 am.

What to Photograph

Well, the stars, of course. Yes, that’s the place to start but don’t think that’s all you should photograph. Including foreground objects such as horizon lines, trees, even water (reflecting the stars) opens up your compositional possibilities. These objects will generally be silhouetted (black) in your final photograph. But, if you wish to illuminate a foreground object in your photograph, the moon, a flash or strobe light, or even a campfire are options depending on the circumstance.

Star Trails around Polaris
Example of Star Trails around Polaris, the North Star.

Polaris, the North Star

If you’ve seen those star trails photographs that form a complete circle and want to create something similar then you’ll need to know where to point your camera. That’s where Polaris, the North Star comes in. It’s the center point in these photographs and it’s pretty easy to locate. And once you do locate it, it’s not hard to find again because it’s always in the same place in the sky. The stars all revolve around it (it’s really us revolving around the stars).

The Big Dipper pointing at Polaris
The Big Dipper pointing at Polaris (North Star)

The easiest way to find Polaris is to use that well know constellation, The Big Dipper. If you draw a line between the two outermost stars of the "cup" of the Big Dipper and extend it out about 5X the distance you should land right on Polaris. You can verify the star is Polaris as it’s the end star on the handle of another constellation, the "Little Dipper" (see photo above). For a really detailed explanation of finding the north star, read this.

Mobile Apps

Finally, I’d be remiss if I didn’t mention there are tons of astronomy based mobile apps (for iOS and Android) that can assist you as well. Personally, I use Wunderground Weather Apps (there are several variations focusing on different weather features) and Deluxe Moon for tracking the moonrise, moonset, and illumination which helps me plan for photographs where I want the moon’s light to help reveal foreground elements.