Dr. Brian Keating
speaker
1,291 appearances
4 recordings
4 series
first heard Dec 2024
last heard Sep 2025
Dr. Brian Keating’s voice in public audio — every appearance, attributed to the second.
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Appearances
Fun fact, which is bigger, the width of a rainbow or the width of the moon? And is a rainbow wider than a half a degree? You ever seen a rainbow?
Roy G. Biv, yeah.
It's the same size. Okay. It's the size of the sun. Okay. So it's a trick question. Exactly. That's right.
There you go. Professor Faust is the test.
Well, I'll tell you something really cool. If you go to the South Pole, which is oversubscribed by a factor of 10 to 1, 10 times as many people want to spend their nine months of their year minimum at the South Pole than we have room for to actually do work at the South Pole. Which means 10 people total, right? No, there's 45 people there. I'm just kidding. I'm just kidding.
And they're all listening to you. So when you want to go there, when you do go there, they actually don't know where the sun is going to set. Remember, the sun only rises and sets once a year, right? So it's one day and one night per year, six months long. where the sun sets is unknown. And actually, the days preceding it, the sun is making a big circle around your head.
I've seen this with the moon. So the sun and the moon, they just make a circle. And slowly, after reaching their apex on the first day of summer, which is December 21st for them down there, upside down, eventually it crosses the horizon on March 21st. Around March 21st, that's the first day of fall or when they start... getting ready for winter, they don't know where it's going to go down.
We think of it always going to the west. But where is west at the South Pole? Every direction you look is north. So when this occurs, the actual phenomenon that you mentioned, the green flash, can last for days or can last for hours. So if you really are an aficionado of Huberman protocols and you want to see the green flash, apply to be down there.
But the bad news is you're stuck there for nine more months. So, yes, it's a real phenomenon. Not only can you take pictures of it, but you can see it with your eye. The only correction I would say is you pretty much need to have a perfectly clear day. You can't have any clouds on the horizon. And it's best seen over the ocean. So we're blessed here.
Yeah. So the Earth's atmosphere is actually layered, but it's actually simpler to think about the Earth as being flat. Now, hopefully there's no flurfers out there thinking that Brian Keating is advocating the flat Earth. But imagine this table. We're looking at a table.
Imagine there's a slab of translucent glass on it, and we're sitting on the table underneath the slab of glass, pretty thick glass, right? And you're looking straight up. you look through a minimum amount of the glass, right? Straight up would be zenith at your local horizon. Every direction you're looking is your horizon. You see off the edge of this flat earth in this analogy.
When you look at a slight angle, you're going through more path lengths. of the substrate, of the substance. More glass. More glass. Finally, if you did have this thing extending to infinity, you'd be looking through an infinite amount of atmosphere or glass when you're tangent to the horizon, when you're going parallel to the Earth's surface in this flat Earth analogy.
The Earth's atmosphere is not only made of oxygen. It actually has a lot of particulates. And it's because of those particulates, a lot of them come from dust and a lot of them come from volcanoes and a large amount now comes from human-made sources, pollution and so forth. The more optical depth, the more path length that you look through, the more scattering of the sun's light occurs.
When scattering occurs, the longer wavelength light more easily penetrates through dust, smog particles, even glass. So that goes through easier. And the short wavelengths, comparable to the intermolecular spacing of the smog, the dust, the gas, and the atmosphere, the oxygen, scatters much more efficiently. And so that gets scattered out of the beam of light from the sun.
The sun's light, though, actually peaks slightly in the green. We don't actually notice this because our eyes are – and we're used to thinking of it as very yellow. And the reason for this can be substantiated by – Night vision glasses, what color is the light coming in? It's green, right? The amplified versions of these things. Why? Because your eye is very sensitive to green light.
It's even more sensitive to green light than the yellow light. And that's because the sun, which is what we've evolved to adapt to, being most sensitive to sunlight, is more greenish than yellow.
Exactly, 100% right. So at that green flash, at that moment of green flash, you're seeing two things. One is the sensitivity of the human eyes, slightly maximized to that, but that doesn't explain why photographs see it as well. And the other reason is that most of the yellow light and the sunlight is getting scattered away.
And so you're mainly seeing that green light, but you're only seeing it at the point of maximum scattering, which occurs exactly when the sun crosses the horizon.
I don't think that's in disagreement. I think that might explain the amplification that we see, but then it doesn't explain why you'd see it in a photographic emulsion, right? There's nothing biological about it.
I don't know. It's interesting. The sun also produces tides and produces gravitational effect. But the dominant effect on Earth due to that 28-day, 29-day cycle of the moon is its effect on the Earth's oceans, which produces four tides a day, too high and too low. And actually, Galileo incorrectly used that phenomenon as a way to buttress his argument that the Earth went around the sun.
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