The first and most important part of advice is that 100% Totality is the goal. That is the amazing once in a lifetime moment that people have been talking about. 99% is not anything close to 100%. I have seen it put best by one of the members of on eclipse travel group that I joined when he said matching 5 numbers in the lotto is good. Matching all 6 is life changing! If you can get to the path of Totality, people are traveling across the ocean and driving thousands of miles for this, it is worth it!
A solar eclipse happens when the Moon comes in between the Sun and Earth.
The Earth's diameter is 7,917.5 miles wide, the Moon's diameter is 2,159 miles wide, and the Sun's diameter is 864,575.9 miles wide. The distance between the Earth and Moon is 238,900 miles and the distance between the Earth and Sun is 92.96 million miles (or 8 light minutes.)
Those are large numbers that are hard to wrap your minds around . . . like trying to imagine 100 otters on a plane (thank you John Finnemore*). So let's scale this down a bit.
If the Earth had a 1 inch diameter the Moon would only have a 1/4 inch diameter since it is roughly one quarter the size of the Earth. Now between the Earth and the Moon you can fit 30 Earths. Which means with the 1 inch and 1/4 sized bodies the two would be 30 inches away from each other.
Now to add the Sun into this imagine the Earth was a little larger and had a 4 inch diameter. In order to keep the correct scale the Moon would now have an inch diameter. At that size the two should be 120 inches away from each other. The Sun would be the size of a three story building and would be half a mile away.
Seems impossible right? Something as small as a 1 inch in diameter Moon will be able to block the entire three story sun. Pick a spot in the distance of wherever you are (maybe something large across the room from you). Hold up your thumb like you are giving someone the thumbs up sign, straighten your arm, and hold your thumb in front of your face. Now slowly move your thumb back towards your face as your thumb gets closer to you it will cover more and more of the chosen object. Once it gets to the correct distance it will completely cover the object. That is how a solar eclipse happens.
Now I wrote that the solar eclipse happens when the Moon travels between the Sun and Earth. But we all know the Moon orbits the Earth and one lunar cycle is 29 days. So there is a point every month when the moon is positioned in such a way as to be between the Earth and Sun. But a solar eclipse doesn't happen every month. Why is that? The answer is the Moon's orbit is at a 5 degree tilt. Because of this tilt most times when the Moon crosses between the Sun and Earth the Moon's shadow will fall above or below the Earth. It has to be at a particular point in orbit in order for the shadow to land on the Earth.
Now there are two types of solar eclipse. There is the partial/total eclipse that we will be experiencing on Monday and there is an annular eclipse.
Annular gets its name from the latin word anulus which means ring. It is named that because the most famous moment of that type of eclipse is the 'ring of fire'.
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| sciencealert.com |
Now not only is the Moon orbiting the Earth at a 5 degree tilt but it also follows an elliptical path so at some points the Moon and Earth are closer to each other (perigee, or 221,000 miles) and at other points they are further (apogee, or 252,000 miles). Remember before with your thumb? If the Moon is too far away from the Earth it will be too small to cover the Sun. It has to be at the closest point in its orbit in order to be able to cover the Sun and cause a total eclipse.
The entire contiguous states will experience at least a partial eclipse as we fall under the penumbral shadow of the moon. Only a 70 mile wide band will fall under the umbral shadow and experience Totality. This band will go from coast to coast starting in Oregon and leaving the land in South Carolina. The Moon's shadow will take 100 minutes to travel the entire distance of the states and touch 14 different states. Less than 1% of Earth's surface will be under this band. That is how rare it is to have one so close. A lot of times these eclipses will take place over an ocean or in a less densely populated (or unpopulated area).
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| Greatamericaneclipse.com |
Now some important dates for US solar eclipses:
The last time a solar eclipse travelled from coast to coast in America was 1918.
The last time a total solar eclipse passed through the 48 lower states was Feb 26th, 1979.
The last time a total solar eclipse touched the USA at all was July 11th, 1991, when an eclipse passed over Hawaii.
The last time a total eclipse passed over TN (my home state) was August 7th, 1869.
The last time a total solar eclipse passed over Nashville, TN (where I am) was in 1478.
On average it takes 375 years for the same location to repeat.
Now before I start trying to describe what will be experienced during Totality I need to take a moment to mention eye safety. We all know not to look at the Sun we live our daily lives constantly managing to not blind ourselves by the Sun. But an eclipse is a novelty. You don't have pain receptors in your retina so you will not feel pain if you injure your retina and the damage may take a few hours to develop. So you may try and take a quick glimpse at the Sun and think that wasn't so bad. Maybe look around and realize you are seeing normal so be emboldened to look again this time for longer. It's a false sense of safety. You could be doing damage and not know it. Never never never never never look at the Sun. There are safe ways to view the eclipse. For example several companies have been producing eclipse glasses that meet the requirement of ISO12312-2 filter for direct observation of the Sun. Even wearing those glasses you should look for three minutes max and then give yourself a break. You can also use shade 14 welding glass. However if you don't have either of those things by now you will have a hard time finding them.
There are other methods for watching the partial phase of the eclipse. For one you could watch it reflected in the water. The water will cut down glare enough to make it safe to look and you would see in the reflection as the Moon's disk covers more and more of the Sun. You could also use something as simple as a colander and watch through the pinholes made from shadows on the ground. Even the shadows of tree leaves will begin to be crescent shaped as the Sun is covered up. But you only need these methods and tools for the partial phase. If you are in the path of Totality you will not need anything to view the total eclipse.
Now I get to the real fun part! Describing what we can expect to experience during the three hours of eclipse. First there are 4 important moments C1, C2, C3, C4.
C1- First Contact. This is when the Moon's disk first begins to cover the Sun. This is the start of the partial eclipse and you need your glasses to view the Sun directly. Now at first you won't notice anything and in fact a partial eclipse could pass without you ever noticing it. I remember in NY in 1994 thinking I should do something, make a pinhole projector with paper plates, to see the eclipse but I never actually did do that. This phase lasts for a little under an hour and a half as more and more of the Sun is covered. Eventually you will begin to notice some darkening and the shadows will begin to change like I wrote before you will see mini-eclipses in the the trees shadows. Nature will begin to react as well. Birds will begin night songs and head back to their nests, crickets will start to chirp, larger animals may begin acting like it is night. I am performing an experiment of my own. I bought a Morning Glory vine and a Moon Vine. The Morning Glory opens in the morning with the Sun and closes at night. The Moon Vine is the opposite. I am going to try and see (if I have blooms on them) if the plants will react to the partial and total eclipse.
You also may notice a change in the temperature as it could drop on average 5 degrees. Also the wind may change directions. This is called Eclipse Wind and was noted by Edmund Halley during the 1715 eclipse when he described, "a chill and damp that brought some sense of horror to the spectators." The cause of Eclipse Wind was not fully known and verified until March 20th, 2015. when during a partial eclipse over the UK researchers from the University of Reading and 4,500 citizen scientists took detailed notes and information about changes in the temperature and wind. Analysis of the data showed that Eclipse Wind was caused by changes in the boundary layer, the area of air that separates high-level winds from the ground. Giles Harrison, one of the University researchers stated, "warm air stops rising from the ground, causing a drop in wind speed and a shift in its direction."
Another phenomenon that will be experienced in the last 90 seconds of the partial phase is called Shadow Bands. I have to admit I have been obsessed with them ever since I learned of them from a video by a blogger:
Now these are not seen or reported with every eclipse perhaps because so many people are busy looking up in that last minute that they do not look. The Shadow Bands are described as thin wavy lines that look like snakes which undulate on plain surfaces. They have also been referred to as Diffusion Bands. I assume it has something to do with the Earth's atmosphere causing some kind of interference and the way light is seen through it but I don't know. And neither does NASA right now. If you go to their website you will see a list of questions such as:
Do the shadow bands move in the same direction across an area?
Do they move parallel or perpendicular to the direction of the sun?
Do they follow the geographic direction of the wind?
Do they maintain the same speed?
What is the distance between the bands as they move?
How does intensity change?
Just like in 2015 when ordinary citizen scientists observed the wind and helped researchers give the cause maybe through many observations scientists can get some answers about these Shadow Bands?
Now I just put up a white vinyl fence around my property so I am hoping that I will be able to capture the Shadow Bands on video. We will see.
Now we are at the point where Totality is seconds away. The Sun is almost completely covered by the Moon and the phenomenon called Bailey's beads occurs. This is named for Francis Bailey an astronomer who first described the beads during the May 15th, 1836, eclipse. They look like a string of red beads of light around the Moon's disk and that is light coming through the craters of the Moon's uneven surface.
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| Fred Espenak www.Mreclipse.com |
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| Fred Espenak www.Mreclipse.com |
Immediately following the beads is what is called the Diamond Ring effect when the Sun's light is focused through the last crater of the Moon and flashes out looking like the diamond on a ring.
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| Fred Espenak www.Mreclipse.com |
Immediately after that is C2- Totality! Now if you are not in the specific band that will be able to see the total eclipse then what would happen now is more and more of the sun would return to sight as the Moon's disk passes over the Sun. If, like me and countless others, you are in or have travelled to the path of Totality then you will be able to see the Corona or Crown of the Sun.
The Corona is a hot outer layer of the Sun described as a white/silver/blue light given off by the Sun that can only be seen during a total eclipse because normally the Sun is so bright. It has been described to look like a cross emitting from the Sun or resembling the wings of a bird. This is an amazing moment. In videos you hear people cheering at the moment. It's been described as overwhelming. I'm pretty sure I will cry.
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| Fred Espenak www.MrEclipse.com |
Just like the 2015 eclipse gave researchers an opportunity to measure and record changes in the wind this eclipse is going to give researchers an amazing opportunity to study the Corona. You can count on the fact that during the entire 100 minutes that the Moon's shadow crosses the US the Corona will be recorded by photographs and video. Changes in the strength, duration, and direction of the emitted light will be noted.
Also visible during the Total portion of the eclipse will be the night sky . .. . except it will be during the day :-) planets and stars will be visible! Once the Sun is covered Venus will become the brightest object in the sky. Fainter and harder to find will be Jupiter, Mars, and Mercury. Also you may be able to pick out bright stars like Capella, Sirius, and Betelgeuse. Here is an image from Sky and Telescope Magazine as to what the sky above Hopkinsville will look like.
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| Sky and Telescope Magazine |
If you are in Hopkinsville, KY you will have the longest time of Totality so 2:44 to enjoy all you can of this amazing sight.
Now we reach C3- Residual and the whole thing repeats in reverse. The Diamond Ring will flash, Bailly's Beads will reappear, Shadow Bands will wiggle around on the ground, and the lighting and temperature will return to normal over the course of an hour and a half and then it will be C4 and the eclipse will be over.
Now that is what we know about Solar Eclipses today. But in ancient times (well and not so ancient times) the Solar eclipse was viewed very differently. It wasn't until the 1700's that people started looking to an eclipse as a moment to be viewed and travelled too. For many ancient cultures the eclipse was a cause of anxiety. It was a bad omen or sign of trouble yet to come. They feared the eclipse. That was a fear like many fears born from a lack of knowledge. They couldn't explain it, didn't understand it, and it was jarring. Night in the middle of day! It is still jarring to some people today and that is knowing what we know now. An eclipse brought a feelings of fear and foreboding but it is that fear and foreboding that has lead to modern astronomy as we know it today.
Most of the myths and stories told by ancient cultures to explain the eclipse are violent, many involving something eating the sun. This was a way of explaining what was not understood. For example the Pomo tribe word for eclipse means "Sun got bit by Bear". A bear was walking on a journey and began to fight with the Sun. As the two fought the bear bit the Sun causing the eclipse. In Vietnam a giant frog, or evil spirit described as a frog, tries to eat the Sun. For the people of Mongolia it was a dragon called Arapto who tried to eat the Sun. In ancient Korea a king from far away sent a dog, Bulgae, to capture the Sun and Moon. The dog tried to bite the Sun and discovered it too hot. He tried to bite the Moon and discovered it was too cold. He returned to his master empty handed but was sent back out again to continue and try and catch them.
The ancient Norse believed the Sun and Moon were two entities named Sol and Mani who travelled across the sky in horse drawn chariots. They were constantly chased by sky wolves called Skoll and Hati. An eclipse would happen when the sky wolves caught one of the two. If the wolves ever caught and ate both of them it would signal the beginning of Ragnarok.
In some stories the gods were fighting with each other like the story told by the Inuit of the Arctic where the sun goddess Malina was fighting with her brother the moon god Annigan. As she walked away from the fight he chased after her and when he catches her there is a solar eclipse.
Ancient India combined eating and fighting with their particularly gruesome eclipse story. The god Brahma told the other gods and a group of super-humans (asura) that at the bottom of the ocean was a potion that would grant anyone who drank it immortal life. The catch was that the two groups had to work together in order to reach it since neither group had the ability on their own. Well it took a few tries but eventually with the aid of a tree and a mountain they were able to recover the potion. Now the god Vishnu decided to try and trick the asuras so that the gods could have the potion all to themselves. Vishnu disguised himself as a beautiful maiden and had the two groups each form a line so that the potion could be distributed evenly. However while the asuras were distracted he began to only give the potion to the gods. One of the asura, Swarbhanu, realized the trick and joined the line of gods. Vishnu handed him the potion and he very quickly began to drink. The Sun and Moon realize the deception and try to warn Vishnu. So Vishnu becomes enraged and cuts of Swarbhanu's head. However Swarbhanu had already begun drinking the potion so his head became immortal while his body died. Now his immortal head chases the Sun and Moon seeking revenge. When he catches them he eats them. But being only a head with no body they fall out his neck and take their place back in the sky.
The stories however aren't always violent. According to the Aborigines of Australia the Sun is a woman and the Moon an man. When they come together in an embrace there is an eclipse.
Behind every story is a little bit of truth. The myths show that even the ancients understood there was some kind of celestial movement causing the eclipse. There was something in that motion that couldn't be explained and so was attributed to gods or other powerful beings but the idea of the Sun and Moon embracing shows movement. But there was knowledge that they lacked. Nicholas Copernicus (1473-1543) hadn't put forth his evidence for a heliocentric universe. Johannes Kepler (1571-1630) hadn't yet discovered his laws of planetary motion including the fact that planets followed an elliptical orbit. Newton hadn't published his Theory of Gravitation (1687), Edmund Halley hadn't yet used Newton's theory of gravitation in 1715 to prove Kepler's planetary motion and Einstein hadn't improved on all of that yet with his study of Relativity (1915) and spacetime.
Those discoveries of modern astronomy and physics have their roots in the fear and anxiety that solar eclipses caused ancient civilizations. The ancients didn't have those answers so they had to make them up. The ancient Indians tracked the progression of the Sun, Moon, and five visible planets (Mercury, Mars, Venus, Jupiter, and Saturn) and then they added the paths of Rahu and Ketu (the head and body of Swarbhanu) called dark planets because there was something they could not explain in the movements of the bodies they observed.
Because the ancients so feared the eclipse they needed to learn how to protect or strengthen themselves from whatever was to follow. And in order to protect themselves they needed to know when they would happen. The Ancient Babylonians would substitute someone for their king before an eclipse in hopes that whatever bad omen the eclipse foretold would befall him and not the real king. For months sometimes the impostor would dress, act, and eat as if he were the true king. So how did they know when to pick a new substitute for the king? Through their observations they discovered a pattern called the Saros Cycle, a period of just over 18 years (6,583.3 days to be exact). Any two eclipses separated by one Saros cycle will share a similar geometric.
The Saros cycle is also seen in works by the ancient Indians and ancient Chinese. While it didn't allow them to know the cause of the eclipse it did allow them to recognize the pattern and therefore predict them... most of the time. There is an epitaph found in China to two astronomers which has been translated to:
"Here lies the body of Ho and Hi
Whose fate though sad is visible,
being hanged for they could not spy,
Th' eclipse which was invisible."
possibly referencing 2137 BC eclipse
The Ancient Chinese emperor would perform rituals and prepare special meals leading up to a solar eclipse. The people would bang drums and pots in order to try and scare away the dragon which was said to be trying to eat the sun, the word for eclipse means to eat. Astronomers would write statements or questions on Oracle Bones, pieces of bone or shell, and then place a hot bronze pin on them and read the cracks. One Oracle Bone that was discovered read:
"Three flames ate the sun, a big star was seen." June 15th, 1302 BC.
The three flames may refer to prominences from the sun and the star could have been any of the visible planets. By recognizing patterns the ancients were able to prepare and their preparations have left behind records that can be used today to not only build a better understanding of what they saw in the sky but overall history. In China there was a Chronology Project where experts in history, linguistics, archeology, and astronomy came together to try and discover exact dates of major events in history. For example there was a rough idea as to when the final battle between the Shang dynasty and the Zhou dynasty took place. But it was a span of 112 years. Using carbon dating on some Zhou pottery that time was condensed to 30 years. Then astronomical observations were used to discover the exact date of the battle and the birth of the Zhou Dynasty as Jan 20th, 1046 BC.
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| sample of an Oracle Bone |
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| Antikythera mechanism |
Thales of Miletus, a Greek philosopher and astronomer, has a story about him that says he fell down a well while star gazing, but it was worth it since he was able to use mathematics to predict the May 28th, 585 BC, eclipse.
Greek history is littered with references to Eclipses. During the Peloponnesian War Nicias was planning a retreat but stopped when an eclipse occurred. As a result Athens suffered a huge defeat to Sparta. Herodotus, Greek historian, noted that the 585 eclipse stopped a battle between the Lydians and Medes.
In Homer's Odyssey Theoclymenus warns that "The sun has been obliterated from the sky, and an unlucky darkness invades the world." 300 years later Aristotle was quoted as saying, "If someone had said he had performed his ablutions in vain because the sun did not go into eclipse, he would be ridiculous. Solar eclipses are not what washing is for," 4th century BC
And on the other side of the world the Mayans made predictions that went beyond their civilization. They were off by only one day in a prediction for the July 11th 1991 eclipse.
Finally I have said that I have never seen Totality and that is true but I have seen many versions of the Corona and the eclipsed sun through art.
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| Sketch of 1800 corona |
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| Image from 1991 eclispe |
Both pictures show the Corona looking like the wings of a bird.
Nazca pottery shows the solar eye surrounded by emitted light of the corona.
A Steele found in Kalah, Iraq shows a winged sun with a cross in the center.
Now that you have read all of this if you are thinking, "man if only I had known sooner what this event was, how amazing it could be. If I had only known I would have taken off work or planned in a way to see it." I'm going to give you good news. We won't have to wait 375 years for another solar eclipse. On April 8th 2024 there will be another American eclipse. This one will travel from Texas to the north east. Not quite the amazing coast to coast action of this one but still a second chance for all those who decide that next time will be there time.
Also save your glasses on November 11th 2019 Mercury will transit the sun so you will need the glasses again!
* The reference is to a British radio program called Cabin Pressure written by John Finnemore and featuring the voices of John Finnemore, Benedict Cumberbatch, Roger Allam, and Stephanie Cole.
Resources:
Great American Eclipse for maps and general info
Mr. Eclipse for photography information
Eclipsophile for weather and climate information
Being in the Shadow psychologist and eclipse expert
Mercury Transit
The Mask of the Sun by John Dvorak
In the Shadow of the Moon Anthony Aveni
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