Lunar Eclipse over Longs Peak: a How-To
Updated: Feb 15
Order a print of Lunar Eclipse over Longs Peak
Photographing the lunar eclipse over Longs Peak was a challenge on many levels. You can read about the physical challenge of reaching my shooting location atop Twin Sisters in the middle of the night here. This blog post will describe how I planned the shot to be in the right place at the right time, how I shot the component pieces, and how I assembled the final image in Photoshop.
My plan was to shoot a series of images, starting before the moon began to enter Earth’s shadow, and continuing until the eclipse ended. The first step, therefore, was to find out when the eclipse would begin and end. That information is available in many places on the web. I used www.timeanddate.com. To be specific, I needed to know when the partial eclipse would begin, when totality would begin and end, and when the partial eclipse would end, all for my location in Colorado.
Next, I needed to know where the moon would be, in terms of azimuth (compass bearing) and altitude (angular elevation above the horizon), at the beginning and end of the eclipse. For that information, I turned to Photo Ephemeris Web. I knew the partial eclipse would begin at 4:16 a.m. If I wanted to shoot one frame every five minutes, and I wanted six images of the fully illuminated moon before the partial eclipse began, I would need to start shooting at 3:45 a.m. So I set the date and time of Photo Ephemeris Web to April 4, 2015, 3:45 a.m., and saw that the moon would have an azimuth of 230 degrees and altitude of 31 degrees.
This screenshot from Photo Ephemeris Web shows the position of the moon at 3:45 a.m., when I started my sequence of moon images. The thin blue line indicates the direction of the moon as seen from the summit of Twin Sisters. Notice that it falls to the left of Mt. Meeker. The thick blue line indicates the direction of moonset. The thick yellow line indicates the direction of sunset, which of course was not relevant in my calculations for my lunar eclipse image.
Further examination of TPE showed that at moonset at 6:47 a.m., the moon would be at azimuth 263 degrees. TPE also showed me that the moon would set just a few minutes before sunrise while it was still partially eclipsed. That meant that during the later stages of the eclipse the sky behind the moon would become increasingly bright and the land would be illuminated by twilight.
Putting all this together, I concluded that the ideal shooting location would be where I was looking at something interesting to the southwest, and where I would be as high as possible, so the horizon to the west would be at my elevation (or close) and I could see as much of the eclipse as possible before moonset.
This screenshot from Photo Ephemeris Web shows the position of the moon when it sets below the skyline ridge at 6:35 a.m., a few minutes before the almanac time of moonset. The thin gray line extending from Twin Sisters towards the gray secondary marker indicates the direction of the moon. The thick blue line indicates where the moon would set above a level horizon.