Crazy Little Thing Called Zodiacal Light

There’s always something new and exciting to photograph! That’s one of the reasons I enjoy night photography so much. With all of Heaven and Earth to explore, a curious and imaginative night photographer never runs out of subjects.

A decade ago, I spent an autumn night in the West Virginia Highlands photographing the night sky. A few hours before sunrise, I saw twilight begin on the eastern horizon. It seemed way too early for it to occur, but seeing is believing and so I started preparing for the morning sunrise shoot. Over an hour later, when I still couldn’t see any color on the horizon, I attributed the light to light pollution from a distant city that had “woken up” in the morning. A few years later, I learned that the phenomenon I had witnessed was called the “zodiacal light,” and it had nothing to do with artificial lights or twilight.

The zodiacal light occurs when interplanetary dust scatters sunlight. In the northern hemisphere, it appears as a faint cone of light above the western horizon after sunset and on the eastern horizon before sunrise. Its light intensity is greater than the Milky Way. Typically, the light is colorless, but in rare circumstances it can have blue, green, yellow, or red hues. If the conditions are right, it is easy to see the zodiacal light, but because it is so faint and occurs near the horizon, most viewers think they are seeing twilight or the light from a distant town, as I did the first time I saw it.

Zodiacal light, twilight, and meteors

The zodiacal light shares an autumn sky with the morning twilight, a meteor, and an Iridium flare. 17mm, f/4, ISO 1600, 25 seconds.

The zodiacal light is easily seen only in the spring and fall in mid-northern latitudes, and only on clear nights without any light pollution from cities or the moon. Those in northern latitudes might not see it at all, while those in the tropics can see it more regularly. In the southern hemisphere, it is best viewed before sunrise in the spring and after sunset in the autumn. In my neighborhood at latitude 35 degrees north, the ideal viewing times are after sunset from mid-February to mid-April and before sunrise from mid-September to mid-November. You can begin to see the light as twilight ends at dusk in the spring and for about an hour afterward. Conversely, in the fall, you’ll want to start looking for it at least an hour before twilight begins.

Photographing the zodiacal light is pretty straightforward. Basically, you do the same thing that you would for any static star scene. Try f/4, ISO 1600, 30 seconds as a starting point. Of course, you can also shoot star trails while the phenomenon is occurring. If you shoot right when twilight is ending at dusk or just beginning at dawn, you can catch the twilight glow on the horizon.

I shot the accompanying image after twilight began and just a few minutes before it became bright enough to wash out the zodiacal light. You can see how someone not familiar with the zodiacal light might think the diffuse white cone is just part of twilight, but as a night photographer you know that twilight light is not white. In addition to capturing the zodiacal light and the first hints of twilight on the horizon, this image records a meteor streak on the right side of the frame and what I think is an Iridium flare within the zodiacal light itself. The latter might be another meteor, though.

One of my favorite rock bands from the 1970s and 80s was Queen, and one of my favorite songs by the group was “Crazy Little Thing Called Love.” Who’d a thunk that 32 years after that song hit number one on the Billboard chart, I would learn that Queen’s master drummer, Brian May, had love for astrophysics. (Oh, the irony of a rock musician moonlighting as a scientist!) In 2007, May completed his PhD thesis, A Survey of Radial Velocities in the Zodiacal Dust Cloud. I guess you could say of Brian May, another one bites the dust!

Hmm, if it’s okay with you, I think I’ll stick to PHOTOGRAPHING the zodiacal light and singing along to “Crazy Little Thing Called Love,” “We Will Rock You,” “Bohemian Rhapsody,” and all those other great songs from Queen. You guys can figure out what the *@#$%^& a radial velocity in a dust cloud is!

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