In May, I captured a full arch Milky Way image at the Grand Staircase-Escalante National Monument
Understanding Airglow
Airglow is a faint, natural emission of light by a planet’s upper atmosphere, driven by solar radiation and chemical reactions, making the whole sky glow softly even in the dark.
Colors and Chemical Reactions
- Green Waves: Excited oxygen atoms at altitudes of 90–100 km release this green light (557.7 nm) as they shed energy.
- Orange/Red Undercurrents: Sodium atoms and hydroxyl (OH) molecules at similar heights create the warm orange and deep red tones lower down.
- Gravity Waves: The rippled, wavy patterns reveal atmospheric gravity waves—physical ripples in the air caused by wind or weather systems passing over the mountains below.
At an altitude of 90 km, airglow is typically a smooth, uniform layer of faint light. When a gravity wave moves vertically through this zone, it disrupts the gas molecules.
- The Wave Crest (Bright Bands): As the air squeezes together at the top of a ripple, it packs the oxygen and sodium atoms tightly. This sudden increase in density triggers a higher rate of chemical reactions, making the airglow much brighter.
- The Wave Trough (Dark Gaps): As the air sinks and spreads out in the valleys of the wave, the atoms part ways. The chemical reactions slow down, causing the airglow to dim.
This alternating cycle of squeezing and spreading shapes the glowing gases into the striking, synchronized rows of green and orange bands stretching across your horizon.
11-Year Cycle
- Solar Maximum Alignment: Airglow does not require active solar storms like auroras do, but it is deeply linked to the Solar Cycle. During years of solar maximum, increased ultraviolet radiation significantly heats the upper atmosphere.
- 40% Brightness Boost: This surge in energy triggers many more chemical collisions. Scientists have proven that airglow is up to 40% brighter during a peak solar phase compared to a solar minimum. Tracking the sunspot count gives you a baseline for baseline brightness.
Gravity Wave Patterns
- The Trigger: Strong winds sweep across large terrain features, like the Grand Staircase-Escalante or the nearby Rocky Mountains.
- The Push: The mountains force a large volume of air upward.
- The Oscillation: Once the rising air hits a stable upper layer, gravity pulls the dense air back down. As it drops, it warms up, becomes lighter, and rises again. This mechanical bouncing motion creates a continuous vertical wave pattern.
Diamond Dust Snow and Incredible Timing
I took those images at 2:00AM on May 20, the last possible date to get a full arch Milky Way in 2026 due to lunar conditions. The next day the moon would interfere, and the next month the arch too high.
When I got up at 1:00AM it was sleeting or snowing so I thought. I feared the night was ruined. It turns out this sleet was diamond dust (or clear-sky precipitation).
It was a totally clear night, and a cold front passed through earlier in the day.
The phenomenon is officially called diamond dust. It maps to a rare, highly energetic chain of atmospheric events that directly supercharged the airglow in my shot.
The “Diamond Dust” and Cold Front Connection
- The Inversion Layer: The cold front that passed through earlier in the day dumped cold, dense Arctic air right onto the desert floor. However, the air higher up remained relatively warm and humid.
- Clear-Sky Freezing: Moisture mixed down into the freezing surface layer, causing the water vapor to instantly crystallize into microscopic, hexagonal ice prisms right out of thin air.
- The Sleet Illusion: Because there were zero clouds overhead, these tiny crystals floated down through the starlight, lightly striking my gear or skin and mimicking a very fine, gentle sleet.
How the Cold Front Ignited the Gravity Waves
A passing cold front acts like a massive atmospheric snowplow. When that dense wall of cold air collided with the warm air and plowed over the rugged topography of the Grand Staircase-Escalante, it generated violent mechanical waves.
The energy from that front didn’t just stay on the ground—it propagated vertically like a massive shockwave. By 2:00 AM, those turbulence waves traveled all the way up to the 90 km boundary layer, forcefully compressing the oxygen and sodium atoms into the intense, distinct green and orange compression ripples captured across the horizon.
Perfection of May Midnights
In mid-to-late May at 2:00 AM, the core of the galaxy stretches from the southeast to the northwest before it climbs too high overhead later in the summer.
By shooting in a single row right as the front left behind scrubbed, crystal-clear air, I eliminated the atmospheric haze that normally muddies deep-space exposures.
The air air glow, diamond dust, and gravity wave explanations above are with AI assitanance.
Camera Sensor Enhancement
I have a modified EOS R5 camera from Spencer’s Camera to capture more of the red H-alpha wavelength.
While it primarily boosts the magenta H-alpha emission nebulae, it also helps pull out the faint, deep-red hydroxyl emissions in the atmospheric glow, making the overall color gradient much more vivid.
The above image is a combination of three full sets of 220 degree panoramas, stitched and blended together.
Each pano set is 24 images. The land is three focus-stacked images, 8-wide. The night images are three-stacked to reduce noise, focused at infinity.
A third set of 24 images captured a very specific and narrow band of red known as H-Alpha.
That’s 72 blended images in total to make the above image.
Dealing with 250,000 Stars, Literally
Here is a snip of the central portion of the milky way with hundreds of thousands of stars, mostly unwanted.
The above image snip is before I blended in the H-Alpha sequence.
The program I use for merging the 3-image astro stacks tells me how many stars it finds. In one vertical panel (1/8 of the horizontal sequence) the count was over 44,000 stars.
This is a result of a super-fast lens and accurate tracking. You end up capturing more stars than you want. Some like all the stars. Most, including me, would rather see more of the Milky Way structure.
There are apps that will remove stars. They don’t do a perfect job, but I have a way of cleaning up errors.
The H-Alpha pano sequence captures only red at a specific wavelength, blocking all other light.
It looks like this
The glow of the red nebulas stands out.
The trick is adding back only the desired H-Alpha nebulas not the background red color.
Working with H-Alpha Filters
H-Alpha filters block so much light they are near-impossible to focus in the field at night for Canon users. I eventually gave up trying.
Instead, I focus during the daytime on an object 35 miles away (a tiny part of Zion) that I can see from my backyard. Then I leave the camera turned on and tape down the lens so the focus does not shift.
Sony users have a night view in their camera allowing easier focus.
Blending in the H-alpha filter is another treat, and so is getting it aligned with the regular milky way shot. That’s two more learning processes (alignment and blending).
Working With Star Trackers
I use a Benro Polaris star tracker.
A star tracker is a device that rotates at he same speed as the Milky Way. If you use a tracker, you must take the land separately or the land will be blurry.
I generally take the land images after sunset in the blue hour so there is no direct light on the scene.
If you are considering getting a star tracker (or are simply interested in more details of what it takes to get a shot like like this), please see my article Astro Photography Tips and a Benro Polaris Star Tracker Review
My post also covers camera modifications and H-Alpha filters. You cannot capture any the H-Alpha emission without a specially modified camera.
Dan Zafra has some excellent courses and a review of the Benro Polaris. I link to his courses and review.
Please check it out.
I started working with the Benro Polaris in March. It was not until May that I was finally able to take images in the field using it. I lost many milky way night sessions struggling with it.
Are Star Trackers for You?
The answer mostly depends on your time commitment. Some of the learning curves are steep. There is hardware, software, and many apps to learn. But one does not need specially-modified cameras or H-alpha filters to benefit from a tracker.
So this is not an all at once, all or nothing, kind of thing.
I go over learning curve of the Benro Polaris, star trackers in general, camera modifications, and H-alpha filters in my review.
Related to the Benro Polaris, there are many Canon-Nikon issues that Sony users don’t have. I also go over those issues and solutions in my post.
Equipment
These images were taken with an exceptionally fast RF-mount 20 MM F1.4 Canon lens at F 2.0 (F1.8 for the H-alpha set) on a modified R5 camera.
It’s one of Canon’s best lenses ever, and a nice compromise between 14MM and 20MM for taking wide-angle panoramas.
14MM makes backgrounds too small for my tastes, and 24 is a tad too narrow.
Even at F1.4, focusing with the H-Alpha filter is very difficult.
I also used a Capture-the-Atlas Night Filter.
The filter cuts through light pollution to recover contrast in the night sky, and gives a subtle boost to Hydrogen Alpha nebulae. It is compatible with both standard and astro-modified cameras.
I only use the filter for the sky, not the land.
Those interested in my equipment and recommendations can find it here: Mish’s Equipment List.
To Dance Beneath the Diamond Sky with One Hand Waving Free
To Dance Beneath the Diamond Sky with One Hand Waving Free is a line from Bob Dylan’s Mr. Tambourine Man.
It was an amazing night
Perfect conditions and I have never seen air glow like that
Some of that is better equipment and better technique, and some was luck. It was an amazingly clear night in the middle of May and it was unusually cold with very clear air.
When my alarm went off and I got up, I thought it was snowing or sleeting. Because of hotel lights I could not tell that it was 100% clear. I was hoping it was a passing cloud.
Escalante is one of the darkest, easily assessable places in the US.
This is a very wide image. You can see the big dipper which is NW and the N star which is N. The core of the Milky way is SE and to the right of that is S. So that is a very wide view over 180 degrees.
My next set of posts will be more Milky Way images. I have some from Bryce Canyon and Escalante.
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Addendum
I reprocessed the H-alpha layer and added an improved star-mask on top to pick up more stars.
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Mike “Mish” Shedlock