Why Solar Eclipses Are Such a Big Deal

Here’s a sanitized version of the YouTube transcript:

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Hey, smart people! Joe here. The sun is enormous—10 times the size of anything else in the solar system and 100 times the size of Earth. But Earth is part of a lucky cosmic coincidence. Our moon is 400 times smaller than the sun, but it’s almost exactly 400 times closer to us. This means that to us here on Earth, they appear to be almost the same size in the sky. Because of this coincidence, every once in a while, our tiny moon crosses in front of the sun and blocks its light from reaching Earth, creating a solar eclipse. On April 8th, that’s going to happen right here. The shadow of the moon will pass right over where I’m standing. You won’t want to miss this! The US won’t see another total solar eclipse for 20 years, so this is a once-in-a-generation chance to witness one of the most mind-blowing events in the solar system.

Today, I’m going to tell you everything you need to know to make the most of this eclipse or any future eclipse you have the chance to see. We’ll discuss how to pick the right spots to be in the maximum shadow of the moon, what to bring, and everything there is to see before, during, and after an eclipse. There are incredible things you can learn from an eclipse, whether you’re a scientist or just someone who wants to experience the awe of witnessing an incredible cosmic event.

First things first: if you need any persuading that this is worth seeing, just consider how special an eclipse is in the first place. Eclipses happen because the moon’s orbit takes it between us and the sun, but the moon orbits between the Earth and the sun once a month during each new moon. So why don’t we get an eclipse every month? That’s because the moon’s orbit is tilted a few degrees from Earth’s orbital plane. Eclipses only happen when the moon’s tilted orbit aligns perfectly with Earth’s orbital plane, allowing the moon to cast its shadow on our planet. Between two and five solar eclipses occur somewhere on Earth each year, but on average, any given spot on Earth only gets one total eclipse every few hundred years. Long story short, if you have a chance to see an eclipse, you don’t want to miss it.

The first thing you need to do is pick the right spot. You’ll want to be in the path of totality. Totality is the moment during an eclipse when the moon’s shadow completely covers the sun, and there’s only a small stripe of Earth where you can see that. That’s the path of totality on April 8th across this stripe of North America. Outside the stripe, the moon will partially cover the sun, but you won’t see totality. The closer you are to the center line, the longer totality will last. There are many maps and apps to help you pick a location, and I’ve dropped links to several in the description so you can look for a good viewing spot. The weather, though, is up to you; I can’t do anything about that.

You’ll want to figure out exactly when totality will occur at your spot so you don’t have to do it on the day of the eclipse when you’re overwhelmed with excitement. To get the most out of the eclipse, consider an app like a solar eclipse timer, which precisely times every key moment you should watch for at your location. They’re not sponsoring this video or anything, but it’s a useful app that really works. I’ll leave you a link in the description.

It’s worth pausing for a moment to acknowledge how incredible it is that we can calculate this at all. Eclipses are incredibly hard to predict. Ancient civilizations like the Babylonians, Chinese, and Maya had advanced mathematics and astronomy good enough to construct some of the most accurate calendars in human history, but none could predict exactly when and where solar eclipses would occur. This is not surprising because predicting eclipses involves one of the messiest problems in orbital physics. To predict the exact positions of the Earth, the sun, and the moon into the future requires factoring in every little gravitational influence from every object in the solar system. It’s not just a three-body problem; it’s more like a million-body problem. These wobbling tilted orbits are the literal definition of mathematical chaos.

It wasn’t until 1715 that anyone came close to predicting the time and place of a solar eclipse when astronomer Edmund Halley used giant tables full of future positions of celestial bodies to hand-calculate the timing of an eclipse over London. He was only four minutes off! Nowadays, NASA factors in about 38,000 different overlapping orbital patterns, crunching the data with supercomputers, allowing us to plan our eclipse viewing down to the second. However, even with all that advanced technology, NASA can only precisely predict eclipses for the next thousand years. It’s a problem that’s impossible to solve mathematically; we just hope to get close. So remember that as you plan your eclipse day down to the minute or second—the fact that we can do that at all is already an amazing achievement.

Once you’ve figured out where you’ll be and what time totality is, think about how you want to see it. I must remind you: never look directly at the sun. I want to emphasize that again: never look directly at the sun. Not even with sunglasses, not if it’s 99% covered, and definitely not through a telescope or binoculars. Just don’t do it.

The first thing I’d recommend is getting some eclipse glasses. You can find them from various retailers, but make sure you’re getting the real thing. If you don’t have eclipse glasses, there are still some cool ways to see the eclipse. One simple method is to create a pinhole camera projector. Just poke a small hole in a piece of paper and hold it over a light surface under the sun. You can also make a more elaborate pinhole camera using a box. Trace the bottom on a white sheet of paper, cut it out, and place it inside the box. On the other end, cut two notches in the lid and cover one with aluminum foil. Poke a tiny hole in the foil, then stand with your back to the sun, looking through the other hole, and you’ll see the entire eclipse projected onto the bottom of the pinhole camera.

This works because the light from the sun travels in all directions, but since the hole is so small, only a few rays of light make it through in straight lines. This means rays from the left side of the sun cross through the hole and hit the ground on the right side, and vice versa. You end up with a little flip-flopped image of the sun in front of you. During the eclipse, as the moon moves over the sun, you’ll see this circle turn into a crescent and get smaller and smaller. This is a safe way to watch the eclipse without looking directly at the sun. You can see a similar effect using anything with tiny holes, like a colander, or even light filtering through the leaves of trees.

Watching an eclipse is amazing, even if you don’t understand everything that’s happening. But if you know a little about what’s going on and what to expect, there’s so much to see, and most of it goes by quickly. So the last thing you want to plan ahead is what you’re going to look out for. On the day of the eclipse, with your glasses on, the first thing you’ll see is a tiny nibble on the western side of the sun. Again, the solar eclipse timer app can tell you exactly when this will happen at your location.

As the minutes go by, the color of the sky and the things around you will get a little duller. The wind may even go still as the atmosphere cools inside the growing shadow. About 10 minutes before totality, the sun will look like a thin crescent, and everything will darken. But don’t take your eclipse glasses off yet! You might notice some animals acting strangely. Horses may shake their heads and tails, dogs might get anxious, and birds might stop flying or start singing evening songs. Humans will likely make excited sounds.

In the final seconds before totality, some fascinating things happen. Just before the last sliver of sunlight disappears, the valleys and ridges on the moon’s surface create little beads of light that flicker along the edge of the sun just before the moon blocks them out. In 1836, British astronomer Francis Baily first recorded this phenomenon, and today these beads of light are called Baily’s Beads in his honor. Right before the last bead disappears, you’ll start to see the sun’s atmosphere, the corona. With the sun’s light covered, wisps of the corona emerge as a faint ring around the moon. Then, the last bead of light shining past the moon lights up part of the corona, creating what’s called the diamond ring effect.

As the corona becomes visible, take a look at a light surface like a sidewalk or a white sheet. If you’re lucky, you might see little bands of light and dark squiggling across the surface. These are shadow bands. They’re very faint and resemble the shadow of water rippling over sand. They don’t always happen, and the weirdest thing is that no one knows for sure why they occur. The best guess is that turbulence in the air affects that last narrow sliver of sunlight, similar to what makes stars twinkle.

And then, just like that, the sun is gone. Welcome to totality! Picture this: the moon’s shadow falls on you, and where the sun was, there’s just a black disc surrounded by glowing corona. Everything is as bright as during a full moon. It’s the middle of the day, yet some bright stars and planets become visible in the sky. During totality, you can take off your eclipse glasses and look directly at the covered-up sun. There are some amazing sights you can only see during these few minutes of totality.

Keep an eye out for reddish, cloudy shapes surrounding the disc of the moon. These are called prominences—hot clouds of gas billowing out of the sun along tangled magnetic field lines. You can actually see some of these in the first photo ever taken of an eclipse in 1851. The coolest thing about these prominences is that they only last for about a day, so whatever ones you see during totality are completely unique to that moment.

If you can pull your eyes away from the eclipse for a few seconds, take a look around you. If you can see the horizon, you’ll notice what looks like a 360-degree dawn. This is the edge of the moon’s shadow, visible in the distant sky, where the sun is not totally eclipsed—a sunrise in every direction. The sky will begin to brighten in the west and darken in the east as the moon’s shadow races eastward across the Earth. The sun will be back soon.

Depending on how close you are to the center of the path of totality, you’ll experience anywhere from a few seconds to a few minutes of totality. No matter where you are, it’s a good idea to know exactly when totality ends or have a solar eclipse timer running so you can put your eclipse glasses back on before the sun reappears. Suddenly, you’ll see a glimmer of light peeking through some valley in the moon’s surface on the western edge of the sun—the first Baily’s bead on this side. It might create another diamond ring effect.

Over the next few seconds, more Baily’s beads will flicker in and out. You’ll have a second chance to look for those shadow bands if you missed them the first time. Then everything happens in reverse: Baily’s beads merge into a crescent, the crescent grows, and the sky and surroundings brighten again. Before you know it, the eclipse completely ends. It’s an ordinary day again; the sky is bright, a breeze may pick back up, and animals return to normal. Except for you—you may never be the same after witnessing that.

A total solar eclipse is a different experience for everyone. For some, it’s a chance to witness an incredible cosmic event and immerse themselves in amazement. For others, it’s an opportunity to do science. For centuries, people have studied the sun as it disappears behind the moon, and we’ve learned some incredible things from that. In 1860, eclipse sketches from around the world captured a sort of tendril snaking out from the sun, likely a coronal mass ejection—a blast of plasma that can cause solar storms here on Earth. This may have been the first time one was ever recorded.

In 1868, French physicist Jules Janssen used a spectroscope to observe the sun’s corona during a solar eclipse and discovered the element helium 30 years before it was found on Earth. In 1919, an eclipse helped physicists conduct a major test of Einstein’s general theory of relativity. According to Einstein’s theory, everything with mass curves space-time, so massive objects should act like a lens, bending the path of any light that passes by them. The sun has a lot of mass, so it should bend the path of starlight traveling past it. During the 1919 eclipse, scientists looked at stars very close to the darkened sun and compared them with the stars’ normal positions in the sky. The sun’s gravity bent the light just as Einstein predicted.

We often think of science as a journey from darkness to light, from ignorance to knowledge. But during a total eclipse, it’s the darkness that can be illuminating. However, we won’t always have total eclipses on Earth. The moon is slowly drifting farther from Earth, so hundreds of millions of years from now, it will be too small in the sky to fully cover the sun. After that, there will never be another total eclipse.

It’s incredible that we live on this planet at a time when we can see eclipses at all. Witnessing a total eclipse is the best way I can think of to appreciate how lucky we are to be right here, right now, in this exact moment. Something to think about: if you’re able to, I hope you take advantage of this opportunity this year, next year, or whenever you get the chance.

Stay curious! Thank you so much for sticking around to the end of the video and joining me as I prepare to watch this year’s eclipse. I would invite all of you, but I don’t have enough snacks. A special thank you to everyone who supports the show on Patreon. We literally cannot do this without your help. If you’d like to find out more about how to help us make videos like this one and all the awesome things we do on this channel, there’s a link in the description. We’ve recently shuffled around our perks on Patreon and are introducing some exciting new features, like occasional live streams with me, special posts, and behind-the-scenes looks. Just click the link in the description to learn more. We’ll see you in the next video!

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This version maintains the content while removing any informal language or unnecessary phrases.