At the onset of totality, the terrain along the Lunar limb breaks up the last remnants of the crescent Sun. This phenomena is called Bailey's Beads. On the opposite limb of the Moon, Solar prominences are emerging. Each is many times the taller than the diameter of the Earth.
Partial Solar Eclipse showing the Lunar limb and an enormous sunspot group (AR 2192) visible (Quandt, 2014). Note the uneven Lunar terrain visible silhouetted against the Sun.
Less frequent are Solar eclipses. While Lunar eclipses are caused by the Earth's shadow, Solar eclipses are made when the Moon blocks the Sun. Usually, it is visible as only a partial eclipse, occurring when the Moon does not fully obscure the Sun.
This vehicle, parked at a nearby campsite, proudly displayed the mindset that brought people from all over the world to this rugged Wyoming land. None of us came here for a partial eclipse, even if they are cool too. This time it was totality or bust!
In the days prior to the event, we met visitors from all over the world including; the Netherlands, Siberia, Japan, South Africa, and quite a few from Colorado, Arizona, Michigan and Texas. For one fortunate woman, this would be her fourth total eclipse. But for most of us, it would be an entirely new experience.
Some had brought cameras, but most merely hoped to see the eclipse with their own eyes. For a few minutes on a late Monday morning, a great number of people were about to stop what they were doing, go outside and look up tp see a rare alignment of celestial bodies. This sort of thing does not happen very often.
Solar eclipses tend to be a little more special than Lunar eclipses and once you think about it, it is kind of obvious why. The Earth is much bigger than the Moon, so there is a much greater chance that the whole Moon gets eclipsed by the Earth. When roles reverse, the small size of the Moon means that only a small portion of the Earth will experience any one eclipse.
The most special of all eclipses is a total Solar eclipse. In fact, this particular type of eclipse, where the Moon blocks the Sun in its entirety, is essentially unique to our planet in our solar system and it is the only time it is safe to look directly at the Sun without any filtration. It is only be coincidence that our Moon happens to be about 1/400th the diameter of the Sun and the Sun happens to be about 400 times farther away than the Moon. There is no other place we know of where this proportion of astronomical bodies exists. Furthermore, since the Moon is slowly drifting farther away from the Earth each year, at some point in the future there will be no more total Solar eclipses. They are special indeed!
On average, any one location on Earth experiences a total Solar eclipse once every 400 years or so. That means that most of us who want to see one will have to travel to do so. The first total Solar eclipse that I have had the opportunity to observe took place on August 21st, 2017, and what follows below is a short testimonial to one of the most memorable astronomical experiences we have ever had.
For this event, my family and I travelled to the small town of Guernsey, Wyoming, where we had reserved a campsite for two nights on private land. This location was situated along the narrow path of totality and in late August, the region had good odds of favorable weather, at least as good as any other place on the path where totality could be viewed.
No, I'm not trying to soothe my sinuses. In bright sunlight, I find it hard to see my computer monitor clearly. This picture was taken early in the partial phase of the eclipse when I was checking the telescope focus. For this eclipse, totality would only last 2 minutes and 15 seconds at my location. There will be no second chances.
Now fully eclipsed, this short exposure reveals the inner corona, a feature only visible during an eclipse like this. By my recollection, the pink prominences were only visible to the unaided eye by the gentle hue imparted to the corona closest to the limb. The corona appeared much brighter than shown here.
On the verge of totality...the Diamond Ring! The Suns photosphere is now almost completely obscured and the corona comes into view. As this picture was taken the sky around us rapidly darkened. It resembled deep twilight and for me it was the most profound moment of the event.
As the partial phase continued to advance, the intensity of sunlight decreased slowly at first, then more noticeably. Additionally, the temperature began to drop. Despite having read other accounts, I was not certain just how dark it would actually get in the heart of totality and I donned a headlamp that could be switched on at a moments notice in the event of an equipment problem. This might have been a little over preparation, but I'd rather be known as the guy who wears a headlamp in the middle of the day than the guy who dragged all this equipment out to the wilderness only to blow his chance at photographing the Solar eclipse because it got too dark.
The last few minutes prior to totality passed with growing rapidity. As we gathered the family together and reviewed the rules for safe viewing, the excitement and anticipation of the eclipse was palpable. I also felt a sense of helpless time compression as I made one final change to the camera settings, stopping the sequence capturing the partial phase at 1 minute intervals and switching to the more complicated multi-exposure length sequence planned for totality. Aware of my own fallibility, I checked and double-checked the settings and the seconds flew by like an unstoppable juggernaut. We had wanted to be here, now, to witness this, but there was also a recognition that this thing was approaching rapidly and would be inevitably be upon us. The diminishing light, the dropping temperature, the settling of the winds, and the stunning quiet of nature, it was now time. I initiated the capture sequence and slid the filter from the front of the telescope. As I knelt beside my children, we could hear the distant cheers of other witnesses to the event, already within the umbra of totality. Then, with a last precipitous darkening, we all looked up and saw the onset of totality, the Diamond Ring.
The onset of totality was, for me, the most powerful moment of the event. As a witness, I was aware that this is something that I may only see once in my lifetime. As our attention was fixated on the heavenly alignment, the long wisps of the corona were clearly visible and distinctive. Prominences visible along the Solar limb through a telescope, were only noticeable by the barest glow of pink along the apparent edge of the Moon. Briefly looking around, I saw my children looking up in amazement and encouraged them to keep looking as it wouldn't last long.
The sky had darkened considerably and while the planet Venus was clearly visible to the west of the Sun and Moon, the bright star Regulus was much more difficult to spot. It's proximity to the much brighter corona made it a far more challenging observation. I spent only moments searching for it before being drawn back to the corona for what may be the single most moving sight in all of terrestrial astronomy. Then after barely 2 minutes of exhilarating harmony, the Sun emerged from beyond the Lunar limb and for a moment, the Diamond Ring returned. Then it was over.
From these dark skies a more familiar scene was visible by night. Shown here is perhaps the grandest spectacle of the nighttime sky, the Milky Way, a spectacular compliment the total eclipse that we had travelled so far to see.
Now, aside from being one of my favorite dirty tricks in history, this story also details a rare instance when somebody’s knowledge of astronomy might have made the difference between life and death. Think about it. It’s like every astronomers dream!
Joking aside, this story does illustrate something of the special historical nature of eclipses, in this case a total Lunar eclipse. From our vantage point on Earth, it arises from the occasional alignment of the Sun, the Earth, and the Moon. They happen occasionally and they are striking.
But not everybody knew that long ago. The sudden inexplicable change in the appearance of the Moon was both fascinating and frightening. Terrified and without a sensible explanation, many ancient peoples turned to their traditional beliefs for reassurance. As in the above example, it didn't always help.
There is a story I like to tell to people and it goes something like this...
On June the 30th, 1503, Christopher Columbus, Admiral of the Ocean Sea, was in a desperate situation. His fourth voyage of discovery had been a disaster. Plagued by mutiny and misfortune, his ships were leaking badly and their hulls eaten by worms. With no alternative, he decided to beach his last two remaining vessels on the shores of the island we now know as Jamaica. There, for the foreseeable future, Columbus and his crew would have to negotiate with the natives for food and supplies.
Viewing a total Solar eclipse has been a dream of mine for a long time. I had been planning this particular trip for years and in some ways it was a bit of a gamble. There is never a guarantee of clear weather and I was determined to execute an ambitious photographic plan. We had to travel from the east coast to a rural ranch in Wyoming, bringing all of our equipment and supplies. Most importantly, I wanted to share the experience with my family and balance all those priorities while ensuring the experience was enjoyable to all. We may never see another one, though I doubt this will be the last time I will try.
In the weeks leading up to the eclipse, my wife asked me what I would do if the weather was poor at our site. Would I try to relocate at the last minute to get a better view, despite predictions of apocalyptic traffic? I told her that we had cast our lot. I wasn't going to make everyone get into the car and try to fight impatient crowds of panicked eclipse viewers in a vain effort to find clear sky. I wasn't going to venture off the path of totality and settle for a view of a partial eclipse, even if there was no realistic prospect for totality at our planned site. We didn't come all this way to salvage anything. It was totality or bust!
However, determination alone cannot guarantee success. It was a gamble and I was already mentally fortifying myself in the event of failure. Had we been clouded out, I had decided to use the experience as a new standard for dealing with massive disappointment. Had it happened, we might have said one day, "Remember the time when dad dragged us all the way out to the middle of nowhere to see that eclipse and got clouded out? Remember that? Dad didn't cry when that happened. No, he held it together. So unless it's worse than that, there will be no tears!" Those are some of the thoughts going through my head as I obsessed over weather forecasts, contemplating the likelihood of success or complete and utter failure.
This image was a composite of several different exposures and it shows very closely what a total eclipse actually looks like to our eyes. Note the bright star Regulus visible to the left of the Moon and corona. While the Earthshine dimly illuminating the Moon was not noticeable at the time due to its close proximity to the much brighter corona, it shows up clearly in longer exposures of totality. There is a reason people travel the world to witness these events. There is nothing else like it.
Set across the Sierra Nevada mountains, the eclipsed Moon rises above the clouds. This image was taken from Glacier Point in Yosemite National Park (Quandt, 2015).
Just prior to totality, I started the programmed image capture sequence, removed the Solar filter from the front of the telescope, and took a knee to enjoy this spectacular event with my family. And incase you are wondering, yes, that is a stuffed possum on my daughter's knee at lower left.
A short drive away from our camp site was the historic Fort Laramie of Old West fame. I'm sure this is old hat for the locals, but to us (me) this was some good entertainment. My kids complained until they saw a replica teepee that they could explore. Shown here is your classic looking wagon, much like that used by thousands of 19th Century settlers passing through these parts.
As we packed up our telescopes and camping gear, pulled out onto the highway, and sat idling in what must have been a hundred mile long traffic jam, I pondered the event we had witnessed and what it took to see it. It had been worth the effort and expense. I could not be more satisfied. Yet, elsewhere along the path of totality, there were surely others who had been denied their dream due to weather or some other unfortunate circumstance. I sincerely hope they continue to keep the dream alive and one day find themselves under the shadow of the Moon.
Despite an erratic forecast, the morning of the eclipse was breezy but free of clouds. I spent the mid-morning assembling my equipment, checking my settings, and thinking through my plan. I was going to rely on technology to do the busy work for me while we all enjoyed watching the eclipse. Therefore, it was essential that I start the imaging sequence at a precise time to ensure the short exposures coincided with the onset of totality. To prevent a simple mistake, I wrote the time of the start of my capture sequence on a large piece of paper and placed it on the table directly in front of the laptop keypad. Then, I taped it down so it wouldn't shift or blow away in the breeze, one less thing that could go wrong.
However, after six months the native’s generosity began to wane. Columbus knew a new approach must be attempted. Among the books held in in his cabin was an almanac with astronomical tables. One of them predicted a Lunar eclipse that was, by chance, just days away. So Columbus went to meet with the Cacique, or Chief of the tribe. And at that meeting Columbus told him that God was mispleased with how they had treated the Spanish and as punishment, he would make the Moon appear “enflamed with wrath.” The Chief was not impressed.
A few days later, on February 29th, 1504, the Moon began to pass into the Earth’s shadow. The natives came running down to the ships, howling and laden with provisions. They begged Columbus to intervene so God would not show his wrath upon them. But Columbus said nothing. He sat there, timing the eclipse with an hour glass. Then, 48 minutes into totality, Columbus rose and spoke. He told the natives that God had heard their cries and would forgive them. And the Moon began to pass into the sunlight. The natives were relieved.
By Chad Quandt
Immediately upon the completion of totality, the Solar filter was placed back across the front of the telescope to prevent damage from the heat generated by focusing direct sunlight. After a few moments collecting myself, ecstatic from the culminating experience of the last 2 minutes, single frame images were resumed at 1 minute intervals to record the partial phase, three examples of which are shown here. While I was setting this up, several vehicles from nearby campsites were already rolling, presumably trying to beat the traffic. While my kids might have been ready to go at this point, unsure why I was still hovering over my equipment, I was determined to get my money's worth.
As a child, I remember waking up one night while at my grandparents' cabin near the shore of Lake Winnebago. It might have been 2 or 3 o’clock in the morning. Walking outside on that warm summer night, I was surprised to see the Moon high in the sky and appearing a ruddy orange, with one side distinctly brighter than the other. It dawned on me that I was seeing the totality phase of the Lunar eclipse and part of what made it so special was that I had no idea it was going to happen. At that age, I was already interested in astronomy but was not yet an active and independent observer.
More recently, in 2014 and 2015, there was a tetrad of four total Lunar eclipses visible from sites in North America. I was fortunate to be able to observe and photograph all four of them, mostly in the early morning hours. Every time I see the eclipsed Moon, it's like reliving that experience from childhood, complete with the joy of personal discovery. Yet each Lunar eclipse has it's own unique character, subtle variations in color. Often, the Moon in totality appears orange, sometimes red. This is where the term "Blood Moon" comes from and while popular with the media, the term is usually something of an embellishment.
With the white light filter in place, single exposures were taken at 1 minute intervals throughout the duration of the partial phase, three examples are shown here. Note the string of sunspots visible on the Solar Photosphere. This sequence was terminated approximately 5 minutes before totality in order for me to load and check the more complicated timed sequence intended to capture various features and phenomena of the totality phase, without the use of any filter across the aperture of the telescope.
Just minutes after the image at left was captured, this image was taken using a cell phone. It shows the numerous projections of the eclipsed Solar disc onto a wooden fence, caused by sunlight filtering through the canopy of an orange tree. See, you can take cool astrophotos with a cell phone, a Poor Man's eclipse photo!
The corona is extremely rarified, extremely hot, and here it displays subtle detail. I consider this the classic image of a total Solar eclipse.
Aside from safely seeing the eclipse with my family, my secondary goal was to photograph it and in the months leading up to the event, I had made thorough preparations. First, I selected the proper equipment for the kind of photos I wanted to take. There are lots of great eclipse photos out there and I wanted to create something unique. In looking at some charts showing the projected path of the Sun through the sky, I noticed that it would be relatively close to the constellation Leo during the eclipse. During totality, the darkened sky may allow some of the brighter stars to become visible. The brightest of which was Alpha Leonis, more widely known as Regulus.
To frame the eclipse with Regulus, I chose the WO71 f/4.9 Astrograph. Normally I use this widefield instrument for deep sky imaging, but the well corrected optics would frame the eclipse nicely with enough room to capture the outer reaches of the corona as well as Regulus shining in the deep background. While the image scale provided by the 348mm would not present the disc of the Sun or Moon largely in the frame, tests on the Moon had shown sufficient detail to satisfy given the much wider expanse of the Outer Corona. Provided a tracking mount was used and sufficient exposures to capture the full dynamic range of objects and features of the composition, I thought this would be ideal instrument to capture the unique essence of the event.
The camera was a full-frame Canon 6D DSLR. To protect the optics and camera during the partial phase of the eclipse, I would utilize a film based full-aperture Solar filter. Since the filter provides no optical effects other than reducing the intensity of the Sun's light and blocking harmful UV and IR rays, it would not effect the focus of the image. Furthermore, since it would sit across the aperture at the front of the telescope, it would be easy to remove and replace at the onset and termination of totality. Failure to use an aperture filter in this arrangement outside of the short but safe window during totality would result in a rapid build-up of heat in the rear optical elements of the astrograph and on the camera sensor, quickly damaging them.
While short exposures would be sufficient to capture the Inner Corona, longer exposures would be needed to capture its outer reaches and Regulus. To counteract the Earth's rotation and prevent drifting of the subject during the eclipse, a tracking mount would be needed. Over a month before the event I packed up and shipped my Celestron AVX equatorial mount, along with some additional required equipment, to my cousin in Colorado. This would prevent us from lugging it as extra baggage through the airport, along with the rest of our stuff for a family of four going camping in Wyoming.
With the telescope mounted on a tracking mount (aligned the night before) and the camera operated via an automated sequence commanded by a laptop, the only interaction on my behalf with my equipment would be the timely removal and replacement of the filter across the front of the telescope. Additionally, tests done in the preceding weeks indicated that removing the film based filter would have no discernable affect on image focus. I even brought a micrometer to achieve a blind focus to an accuracy of 0.01mm, provided the air temperature was reasonably close to my testing conditions. To power the setup, I used an DC/AC inverter hooked up to a deep cycle battery purchased locally. Back-up power could be supplied by our rental cars DC outlet. The imaging sequence would include short exposures during the last moments before totality, followed by increasing exposure lengths to allow different regions of the corona to be captured independently. Several of these exposures could be combined into and HDR image approximating the view as seen by our eyes. It was an ambitious plan, but I had tested each element independently except for totality itself.
Last Updated 22 Dec 2020.
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