By now everyone has heard about the big event of the year that will soon be here, and then be gone just as fast. That's the total solar eclipse of 2017. An event that millions upon millions of people around the globe have been planning since last year. What makes this total solar eclipse so different than others that happen though?
The last total solar eclipse that took place that affected a state in the United States was in July of 1991. Many won't remember this though as the path of totality affected only the state of Hawaii and then dropped into Mexico. Earlier in February of 1979, another total solar eclipse took place in the northwestern portion of the United States which was more popular. This years eclipse is cutting straight through the United States from coast to coast affecting millions of people as it will pass through larger cities such as Portland, Boise, Lincoln, Kansas City, St. Louis, Carbondale, Paducah, Nashville, and Charleston. Below is a map where totality will take place (between the red lines, blue line indicates longest duration path).
So what is a total solar eclipse? These eclipses occur when a New Moon comes between the sun and Earth and then casts the darkest part of its shadow (known as the umbra) on our planet. If the Moon covers the entire disk of the sun anywhere on Earth, it is considered a total solar eclipse. Total solar eclipses happen more frequently than thought though. While not visible here in the United States, they do happen around the globe. In fact, the most recent total solar eclipse was just last year of March 9th affecting the Indonesia area. Below is a diagram showing the geometry of a total solar eclipse.
But why don't solar eclipses happen more frequently if the moon comes between the sun and Earth since it orbits around the earth? The moons orbit is tilted with respect to Earth's orbit around the sun by 5 degrees. While it doesn't seem like much, you must remember that the moon is roughly half of a degree in width in the sky. Therefor the moon will miss by either being too high or low which won't allow any type of solar eclipse to take place. An eclipse can only happen when the sun, moon and Earth line up perfectly.
Enough of the facts though! What's some of the features of a total eclipse that makes it worth watching? Many people don't know some of the things to watch for in the path of totality. It's actually not all about watching it become dark. So what then? During a total solar eclipse there are four contacts, commonly refereed to as C1, C2, C3, and C4. There are critical points in these stages.
C1 (or Contact 1) is where the moon first makes contact with the sun in the sky. This will begin the partial eclipse stage which will last some time. There's not anything to spectacular during this stage except seeing the moon move across the path of the sun.
It won't be until right before Contact 2 (or C2) where the show begins. The thing to look for 15 seconds before the sun is totally blocked by the moon is what appears to be a Diamond ring in the sky. This happens when the solar corona (or the outer atmosphere of the sun) becomes visible.
Then, as the diamond ring begins to fade the sun's corona will become more prominent creating a feint ring around the moon which also creates a silhouette of the Moon.
Finally 5 seconds before C2, a phenomena called Baily's Beads will occur. They are called beads because they look like beads of light around the edge of the moon, which are created by gaps in the mountains and valleys of the Moon's surface.
Then C2 (Contact 2) begins for those in the path of totality. This is where the sun is entirely covered by the Moon and darkness sets in. Some say it looks like sunset 360 degrees around your location. If you're in the path of totality this is the only time you can take off the glasses and view the eclipse.
C3 (Contact 3) begins once the moon starts moving away allowing the sun to reappear. The same phenomena before C2 occurs will occur shortly after it starts moving away starting with Bailey's Beads and then the Diamond ring effect. Then we enter into the partial eclipse.
C4 (Contact 4) is when the final edge of the moon stops overlapping any part of the suns disk, and the eclipse is officially over.
There are other things to note though while watching the eclipse too. Over time the light that is available will begin to decrease. The landscape may take on a gray-blue tone. Animals and plants are affected by the eclipse. Animals sometimes become anxious or confused as they begin to act like nightfall has come. Plants may close up as if it were night. Even human behavior changes. Another mystery to scientists even to this day are what is called shadow bands. Shadow bands occur one to two minutes before totality and are very feint ripples on the ground that look like shadows. There are theories about how these are made, but it is still not certain. Not many photographs show these bands successfully as they are very low contrast. Some say they look like hundreds of snakes on the ground parallel to each other, crawling towards you. The picture below show those shadow bands on the white drop cloth.
I've been asked by many people: Is Carbondale, Illinois the best place to view the eclipse? Some would argue it is, while other's say no. What makes Carbondale so important and so interesting? Carbondale will have the longest duration of totality by 0.4 seconds totaling 2 minutes and 41.6 seconds of totality. The next greatest duration is in Hopkinsville, KY that lasts for 2 minutes and 41.2 seconds. So the real question is, is the 0.4 seconds really that important to you? Along with that though, some who plan view the next continental total solar eclipse in 2024 want to see it in the same spot. That's right! In April of 2024, another total solar eclipse will take place and Carbondale is nearest to the crossing center lines of both eclipses. Besides these two points, it doesn't really make up the 'best' location of viewing the total eclipse. Again, some would argue with that statement, but 0.4 seconds to many is not noticeable. Anywhere in the path of totality is going ton be spectacular to watch.
Have you made plans to travel to the path of totality? If not, it's okay. While the Sauk Valley area won't be in the path of totality, it doesn't mean you'll miss everything. A partial solar eclipse will be visible in our area where almost 90% of the sun will be covered. It will begin at 11:50AM and the maximum partial will be at 1:16PM, and it ends at 2:39PM. Unfortunately though you won't be able to see the Diamond ring or Bailey's beads as that will only occur in the path of totality. No matter where you are viewing, make sure you wear the proper eye protection! It is extremely important you purchase an ISO 12312-2 compliant pair of glasses. If they are not compliant, serious eye injuries could occur.
There is a simple way to tell if your eclipse viewing glasses are safe or not. You can..
- Test them by looking directly at the sun several days before the event. The sun, and only the sun, is the only thing you should see and it should be comfortable to look at and not extremely bright.
- You can also test your glasses by looking at an ordinary house lightbulb. The light from the bulb should not be strong enough to see through the eclipse sunglasses.
Most of the counterfeit glasses are being sold online. The glasses being handed out at many events across the nation are considered safe.