Sunday, April 21, 2024

Some Thoughts on the Eclipse

In case you missed it, there was a total solar eclipse almost two weeks ago that was visible along a roughly three hundred mile wide band in North America that stretched from Mexico to Canada. For perhaps the sixth or seventh time in my life, that band just missed the place I happened to be at the time, my home Chicago. 

Meaning that despite my passion for astronomy which began in high school, I have never experienced one of the most thrilling astronomical occurrences of all. 

Nevertheless, we did experience a partial eclipse where from our perspective, the disc of the moon covered about 94 percent of the disc of the sun.

But as everyone who has experienced a total eclipse realizes, the difference between a total and a partial solar eclipse is literally the difference between night and day.

That didn't prevent tens of thousands of folks from gathering in Chicago's Loop where I happened to be, to witness the rare event. The last partial eclipse visible in Chicago was in 2017. The last total eclipse of the sun visible from Chicago took place a few years before I was born, June 16, 1806 to be exact. To put that into perspective, Chicago didn't become a city until 1839.

They say that on average, any given spot on the earth will experience a total solar eclipse about once in three hundred years, so odds are we in Chicago are due to expect one in about 100 years. I could look it up but won't bother as I don't expect to be around then. 

Strangely enough, places not too far from here such as Southern Illinois beat the odds and experienced totality both in 2017 and 2024, further emphasizing the indelible fact that life is not fair.

Of all natural phenomena that thrill, amaze and terrify us at the same time, eclipses, both lunar and solar, are by far the easiest to explain and understand. Go outside on a clear day with two friends, let's call them Luna and Terra, (see where I'm going with this?). Ask Terra to look up at the sun, not for too long of course. Then ask Luna to face Terra, standing between Terra and the sun. From Terra's perspective, your two friends have just created a solar eclipse as Terra's face is now in Luna's shadow and Terra can look in the direction of the sun with no problem as she can't see it.

Then have your friends exchange places. Now from Terra's perspective, she can't see the sun as she's looking in the opposite direction, and Luna's face is much darker because it is in Terra's shadow. From Terra's perspective, she has created both literally and figuratively a Lunar eclipse.

Ah you say but why does the sky turn dark, and you can clearly see the sun's corona during a total solar eclipse?

That's due to an almost freakish coincidence where the sun happens to be about four hundred times the distance from us as the moon, and the moon just happens to be about one four hundredth the size of the sun. This means that from our perspective, the sun and the moon appear to us to be approximately the same size. 

During totality, the disc of the moon lines up precisely with the disc of the sun, completely blocking the light of the surface of the sun from reaching us. However, the moon does not cover up the sun's corona, the outermost portion of the sun's atmosphere, which emits light of its own, albeit much dimmer light than the light from the surface. We don't normally see the corona for the same reason we don't see the stars or the planets at daytime as the blue sky, i.e.: the light from the sun, mostly its blue wavelengths that our own atmosphere scatters, is much brighter than the vast majority of celestial objects we see clearly at night. While firmly inside the moon's shadow, no light from the sun's surface enters the atmosphere, and the normally blue daytime sky fades quickly to black. So, the stars, the planets and the sun's corona are free to shine brightly albeit briefly in the daytime sky during a total eclipse. And of course, we can also see the disc of the moon in silhouette. 



This image is the first-ever astronaut's view of the moon's shadow cast on the Earth during a total solar eclipse on Aug. 11, 1999. The photo was taken by French space agency CNES astronaut Jean-Pierre Haigneré on board Russia's former space station Mir. 
The black, central portion of the shadow is where folks on the ground would experience total eclipse. The outer edges of the shadow where darkness gradates to light, is where a partial eclipse would be observed.

From this amazing photograph, it's obvious that the moon's shadow only covers a small portion of the earth which explains why in any particular place, total eclipses are rare. But if my memory serves correct, from my astronomy class I took back in twelfth grade, I learned that a total solar eclipse occurs somewhere on earth on an average of once per year. Obviously as the surface of our planet is 75 percent ocean, there's a decent chance that a solar eclipse will be visible only from a fairly inaccessible place. 

It also bears mentioning that every minute of every day a total solar eclipse takes place somewhere in not-too-distant space, where the disc of the moon happens to be perfectly aligned blocking the disc of the sun. Of course, in space where there is no atmosphere to scatter the sun's light, the sky is always dark, making the effect much less impressive. So, if you're getting up in age and are jonesing to see one in person before you kick the bucket, I wouldn't bother hitching a ride aboard a commercial spaceship to go see an on-demand solar eclipse, much better to wait a few years and seek one out in some remote part of terra firma.

Lunar eclipses, while not everyday occurrences, are much more common from a terrestrial standpoint thanks to the earth's relative size compared to the moon. In a total lunar eclipse, the entire surface of the moon is swallowed up by the earth's shadow and can be seen from anywhere on our planet which happens to be facing the moon at the time of the eclipse.

You dear reader, probably know all that already as this isn't exactly rocket science.  Heck it isn't even as complicated as understanding the difference between the use of por and para in Spanish. 

So it's a little mind-numbing to see how many misconceptions there are about eclipses among our fellow travelers aboard Spaceship Earth, even among some of our finest minds.

I immediately think of a comment from whom I believe to be the only Nobel Laureate in Astrophysics currently serving as a member of the U.S. Congress, Marjory Taylor Greene, who tied together the recent eclipse visible in the Americas with an earthquake that briefly rocked the U.S. East Coast. The congresswoman with an unquestionably beautiful mind, last week remarked that the unlikelihood of these two rare acts of nature happening on the heels of one another, certainly cannot be a coincidence, but a message from God. 

However, even lesser minds have shown to be susceptible to misinformation about eclipses.

As I suspected ever since the first time I viewed a partial eclipse back in elementary school, many of the dire warnings about the particular dangers of viewing solar eclipses are hooey. Am I saying the warnings are just a conspiracy theory made up by the folks who sell solar eclipse viewing glasses?

Absolutely not. 

But here's the thing. It's never a good idea to look directly at the sun, eclipse or not. Our brains tell us so much as doing so is tremendously uncomfortable as well as completely unsatisfying. Sane people don't stare directly at the sun for more than a second or two not because of the warnings, but because it is too damn painful. This is true even during a partial eclipse. 

Yes, like Donald Trump back in 2017 who is still hazed endlessly about it, I gazed up at the sun for a few seconds at a time a couple weeks ago, just as I did back in 2017, and just as I did during the four or five other partial eclipses I experienced during my life. To the best of my knowledge, I did not permanently nor even partially damage my eyes doing so.

The theory is that because the sky darkens during an eclipse, our pupils naturally dilate meaning that when we do look at the sun, our dilated pupils aren't ready for the instant burst of sunlight, diminished yet still damaging.

It does become perceivably darker as the moon covers up more and more of the sun. But if you've ever noticed the natural contraction and dilation of the pupils, either your own or someone else's, dilation is a rather slow process while contraction happens instantaneously as the sudden increase of bright light is perceived by the brain. So, when you look directly at the sun during a partial eclipse, the pupils are reacting just as they would during no eclipse. 

What's more, looking directly at the sun even during an eclipse where 94 percent of the sun is covered, is still painful enough to discourage you from doing it and reveals practically nothing of the eclipse. 

That said, one should not look directly at the sun for more than a few seconds with normal sunglasses, eclipse or not, as they do not provide sufficient protection from the sun's harmful rays and do enable you to gaze directly at the sun without discomfort for enough time to do some real damage.

That's where the eclipse glasses come in. They block enough light so that unless you are looking at a tremendously bright source like the sun, you cannot see anything through them. But if you use them to look directly at a solar eclipse, they work like a charm.

That is until the partial eclipse becomes total and the light from the corona is too dim. At that point, experts now say, it is safe to take them off and view the magic directly. 

Until the sun comes out from behind the moon's complete shadow that is, when it's time to put the glasses back on.

While I don't have any evidence to back it up, I'm a little skeptical of some of the accounts we keep hearing about how ancient cultures reacted to eclipses. It's a little like the myth we were taught at school that until Columbus came around, everybody thought the earth was flat and that by sailing west from Europe, the ships with everyone on board would fall off the earth's edge. How then did Columbus get anybody to sign up for his suicidal voyage?

A tale that always makes me smile is the one that pits one group, usually colonizers, against another, usually the subjugated. Using their supposed "advanced" knowledge of how things work, one tactic the colonizers might employ to subjugate the subjugated was to use their ability to predict eclipses to demonstrate their power by saying right before they knew an eclipse was coming, that they could make the sun or the moon go away. I'm not saying this has never happened in human history, but what you never hear mentioned is the intended victims saying right after the eclipse, "wow that was a cool trick, do it again!"

You know that had to have happened.

What we tend to forget today is the role the natural world played in people's lives before we came along. Technology giveth and it taketh away. Electricity for one which gave us among many other marvelous things, the electric light bulb. One of my favorite stories is about the grandmother of a good friend of mine who told him that before her house in Maine was equipped with electric lights, she never realized how dirty it was. 

I for one, can't tell you how lost I feel on those rare occasions when our power goes out. 

On the other hand, the electric light bulb has taken away our view of the sky. As a lifelong city boy, I never realized what the nighttime sky really looked like until my early twenties during a camping trip, also in Maine with the same friend. "What is that streak of white light that crosses the sky, is it a cloud?" I asked him. He laughed at me incredulously and said: "It's the Milky Way!" Even though I knew exactly what the Milky Way was, I hadn't a clue that you could actually see it so clearly with the naked eye.

That was only the half of it. By then I had a good handle of the constellations as defined by the brightest stars that were visible from the city. But a couple hundred miles from the streetlights of the nearest city, those same stars I knew so well didn't stand out much from the hundreds of thousands of other stars I couldn't see from home. And I learned on that trip that I could even see with my naked eye something way beyond our own Milky Way Galaxy, the Andromeda Galaxy, some 2.5 million light years away.

With no power, no internet, TV or radio, not even a decent light to read by, people generations before us looked up to, and understood the sky in ways we cannot even dream of. It's no wonder that so much ancient mythology is centered on the constellations and the comings and goings of the planets and other celestial objects that wandered about the sky in relation to the stars which remained forever fixed in place. It was the understanding of those relationships that served as an essential tool to get a grip on an otherwise unpredictable world. 

Most cultures believed that eclipses were bad omens, so it was beneficial to understand them in order to predict and prepare for those events, which they did. They may have beat their drums and shot arrows into the sky to scare away the dragons and demons that were consuming the sun and the moon during an eclipse. We may laugh, but those measures always worked. 

But I suspect the ancient astronomers of every culture knew all along what was really going on.

I've never passed on an opportunity to experience a solar eclipse, even though they were only partial from where I was. This is the third one that happened while I was at work. The first time I had a little home-made pin hole viewer but discovered that a much more impressive way to view the eclipse was via the pinholes made by the fully formed leaves in the middle of summer which projected hundreds of crescent shapes on the ground. I shared that discovery with passersby who to a person were as intrigued by the phenomenon as I was.

I wasn't so lucky in 2017 as there was haze in the sky which does not bode well for the pinhole effect. Instead, I struck up a conversation with a couple who were kind enough to lend me their eclipse viewing glasses. 

This time, the trees were bare but armed with both glasses AND a pin hole viewing device, I returned the favor and shared them with the complete strangers around me, several of them visitors to this country, who again shared my enthusiasm. 

It dawned on me two weeks ago that the real glory of an event like this is the ability to share it with others, perhaps especially with complete strangers. As a society we have removed ourselves so much from nature, that it's truly a wonderful thing to experience one of its most magnificent events, smack dab in the middle of a big city, where you would least expect it. I can't even imagine what a thrill it must have been to be in Cleveland or Dallas or any other big city directly in the path of totality, to experience it together with a large group of fellow human beings gathered to celebrate something so beautiful and awesome.  

Which reminded me of a few important things, we're all in this together as very small cogs, living in a unimaginably massive universe. 

That thought is comforting, scary, and mind blowing, all at the same time.