Location and Event Notes

The total solar eclipse on August 21, 2017 could be seen in a narrow band, roughly 70 miles wide, that stretched across the US, allowing many in the country the opportunity to witness this spectacular display. Although a partial eclipse could be seen in many areas, totality can only be observed in the region in which the moon covers the entirety of the sun’s surface.Inside this region, one stands in the moon’s shadow which, on this occasion, traversed the country from west to east at approximately 2000 miles per hour.

A total eclipse of the Sun is a remarkable phenomenon that should not be taken for granted. Indeed, a total eclipse of the sun can only occur if a planet’s moon appears larger than the apparent size of the sun in the sky and if its orbital path takes it between the planet and the sun.  Our moon is exceptionally well suited for producing a great view of the solar corona, the sun’s atmosphere, from earth. This is because its apparent size in the sky roughly matches that of the sun. Therefore, during a total solar eclipse, it is just big enough to completely cover the sun’s surface, while still allowing almost the entire corona to be seen. The apparent sizes of the moon and sun are so similar that the slight variation of the distance between the moon and earth of a little more than 10% is enough to result in the inability of the moon to fully cover the sun’s disk on some occasions. No other place in the solar system has anywhere near as good a view of this phenomenon as we do here on earth. For example, Jupiter’s farthest Galilean satellite, Callisto, still appears more than 50% larger than the sun as seen from the perspective on Jupiter,  and therefore the moon would cover much of the corona during a solar eclipse. Of course one could not easily view such an event from Jupiter anyway due to the clouds and lack of a solid surface, not to mention that an eclipsed sun on Jupiter would appear about five times smaller in the sky than it does here on earth. The terrestrial planets, other than earth, are even worse. They either have no moons or have moons that are too small to produce an eclipse. Even here on earth eclipses have not always been as optimal as they are now. The moon was once much closer to earth and will be much farther away in the future. In fact, it is estimated that no solar eclipse will be visible on earth in approximately 600 million years.

During totality, the photosphere of the sun (the disk that you see through a solar filter) is obscured, allowing a glimpse at the, much dimmer, atmosphere of the Sun, the corona. The corona is roughly a million times less bright than the photosphere of the sun, but nevertheless still appears quite bright to the eye during totality. The corona is actually hundreds of times hotter than the surface of the Sun and, although it is not known precisely why this is the case, the magnetic fields surrounding the sun likely have something to do with it. These magnetic fields can indirectly be seen by looking at the bright lines in the corona that emanate away from the solar surface. The corona itself is a plasma mostly consisting of electrons and protons at very high temperature, and hence moving at high speed.  The high temperature (of approximately a few million degrees Celsius) means fast motion and energetic interactions, making it difficult for electrons to remain in a bound state, hence the proliferation of charged particles. Additionally, due to the varying magnetic fields around the Sun, the corona is a constantly changing structure whose appearance will vary from one eclipse to the next.

Nothing can prepare one for the experience of witnessing a total solar eclipse. I was fortunate to be able to see one on August 21, 2017. It was unlike anything I had expected and not even a slightest bit like any picture I have ever seen. I was anticipating seeing something amazing in an unusual way, and although it was this, I did not realize that the more prominent feature that would  stand out in my mind would be its sublime and spectacular characteristics. It was, as I try to combine insufficient and inadequate words to convey something that can only be seen to be understood, the most magnificent, and astonishingly spectacular natural sight you can imagine.

During totality, the overwhelmingly bright disk of the Sun was completely covered and only the black disk of the moon remained in the center of the magnificent corona. Venus could be clearly seen. The horizon turned a dark red. This incredible, large, and spectacular light above surrounded by a dark, twilight-like, sky showcasing stars and planets, with a stunning, dark red, skyline along the horizon, providing a backdrop to the mountains in the distance, and a beautiful landscape of it’s own right encompassing the ground around us; this is how I would describe the scene during the brief moments of totality.

The corona of the Sun appears as a very bright, stunningly magnificent, light streaming from the dark edge of the eclipsing moon. The spectacular and surreal nature of the corona truly must be seen to be properly comprehended. It is unlike anything one has ever seen and therefore makes comparisons of little use. Pictures also do no justice to the sight, and although many are quite spectacular, they do not compare to the indescribable luminescence of the corona.

During the partial phases of the eclipse, the ground remained quite bright even when the sun was nearly completely covered by the moon. It appeared just as a cloudy day, but not much darker. Seconds before totality the light intensity dropped precipitously which built anticipation to a climax. During totality, the ground was still not entirely dark, but appeared as it would 30 minutes after sunset or so. The scattered light coming from regions outside the moon’s shadow illuminate part of the sky and ground, as does the corona, although relatively much less I believe (since the light on the ground was quite diffuse and there was a lack of noticeable shadows). The horizon turned a dark red, like what one might see sometime during twilight.

I had wanted to see this eclipse ever since I read about it when I started gaining interest in astronomy many years ago. Little did I realize how many other people also wanted to see it. We had some difficulty obtaining a reservation to stay in the path of totality in Wyoming, even though we tried to get one a year in advance. Apparently most places were already reserved two years ahead of time. We found one of the last available rooms in a place outside East Yellowstone. On the day of the eclipse, we drove to a small town to the south-east near the center of totality. We set out at 4am to avoid traffic which many were expecting to be so severe that it was not a certainty that we would even make it into the band of totality by the start of the eclipse. Fortunately we did (in fact the traffic we experienced was quite mild). We found a dirt road to pull onto which led to a small  hill on the base of which a couple other people had already parked. One of these people was from Italy and had traveled here to see his fourth eclipse. In the couple days leading up to the event, we had talked to people from many different places around the country and around the world who had come to see the event.

I used two cameras to photograph the eclipse. I originally planned to set them both on timers so that I could just watch the eclipse without the distraction of the camera, but once it started I was so amazed by the sight that I could not resist grabbing my camera and shooting a few more images of the colorful sky and surrounding landscape before the brief event was over. I used a solar filter to capture the partial phases of the eclipse with a telephoto lens, and I photographed the corona without a filter during totality. I also used a wide angle lens on another camera to get some of the landscape with the eclipsed sun in the shot.

The last time a total solar eclipse was visible in the contiguous United States was 1979. However, there will be another one in 2024. This will hopefully give people who missed this one another opportunity to catch the event, and give people who already saw it an opportunity to be spellbound by it a second time. I am already looking forward to it.