-by John Hlynialuk
The Sun has been keeping an awe-inspiring secret to itself for about 5 billion years but for 2 minutes and 34 seconds on Aug 21, it was revealed to a group of local amateur astronomers camped out in Nebraska. The secret comes out on the rare occasion of a total solar eclipse, and in recorded history, humans have been let in on the secret only a few hundred times. Even then the viewers had to be in the narrow band of totality so most people on the Earth have no idea of the beautiful sight hidden in the glare of the Sun. On this occasion, since the shadow path crossed the USA, several million people also saw the event and so we were in good company.
The secret is that the Sun has a corona, a "crown" of faint, extremely hot gases streaming away from its surface in a beautiful pattern. It can only be seen on the rare occasions when the Moon exactly lines up with the intensely bright disk of the Sun. Sunlight is blocked out and the sky gets dark enough in the daytime to reveal the delicate pattern of coronal petals all around it. Before the corona appears, however, the last sun rays through valleys on the Moon produce a short-lived glint of sunlight that makes the dark circle look like a diamond ring in the sky. Not once but twice, at the beginning of totality and again at the end with the diamond on the opposite side of the Sun.
In the time between the appearances of the diamonds, the faint rays of the corona fan out. At the base of the corona around the dark circle of the moon's edge are more jewels, bright red prominences, glowing like rubies. We saw three of them this time. The image included here was exposed to show the corona and the prominences are overexposed and not seen. The naked eye however, is a much better instrument to record the view (it is safe to look at the Sun during totality) and you see both diamond rings, the ruby prominences and the entire corona fanning out from the Sun, at the same time during totality! It is absolutely gorgeous! Most first-time eclipse-goers are encouraged to just look and soak in the experience rather than waste precious seconds trying to take photos or focus telescopes.
Photographers who do want to record the event, must be willing to sacrifice the precious time looking at their camera settings and away from the spectacle overhead. Even then it is simply not possible to record both corona and inner features like prominences at the same time. Photographers take a series of images and then create a composite with image-processing software, something the eye does automatically.
Of the group of 26 local eclipse chasers who gathered near Grand Is. Nebraska last Monday Aug 21, the majority had never seen a total eclipse before. So when the first diamond flashed into view, the camp erupted in cheers! When the coronal atmosphere surrounding the Sun appeared, you heard shouts of "corona! corona!" . You could hear the entire campground of several hundred observers cheering and yelling and thoroughly enjoying the awesome experience. Many had tears streaming down their faces.
Me too.
Our campground was occupied mostly by Canadians, who knew a good location to eclipse watch, -right on the centre line and with a good prospect for clear skies at time of totality. In our case, the rains played themselves out a day before and though we had some clouds eclipse day, there were not enough at totality to prevent seeing the Sun's hidden corona. It will be a sight that all will remember for a long time. For now, the Sun's fierce light has hidden the corona from our view once again.
In the recap of the event as we sipped our beverages (Coronas of course), talk came around to the next eclipse as it always does. Eclipse chasing is addictive and we are already thinking about another total solar eclipse which is due in April 2024. In the meantime join us at the Fox Observatory on Sep 6 at 7 pm for the regular Bluewater Astronomical Society (BAS) monthly meeting which will be a recap (with pictures and video) of the spectacular solar eclipse of 2017. It was so incredible!
