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Speaker 1: The best view in the universe is not from the

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Speaker 1: top of the Seer's Tower or the birds Dubai. It's

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Speaker 1: not from some seaside hotel. It's not from the top

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Speaker 1: of Mount Everest. It's from your backyard. On a dark night.

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Speaker 1: You can look up at the universe and see across

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Speaker 1: billions and billions of miles. Every view on Earth pales

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Speaker 1: in comparison to the vista you see across this ocean

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Speaker 1: of space. Though they are impossibly distant, you can still

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Speaker 1: see balls of gas furiously fusing, burning brilliantly enough that

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Speaker 1: they can be seen with your naked eyeball. And if

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Speaker 1: you look closely, you'll notice something incredible. There's a rainbow

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Speaker 1: of stars out there. White, blue, yellow, red. It's a

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Speaker 1: fabulously colorful universe. What does that mean? Why are stars

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Speaker 1: different colors? We'll be digging into the physics and countering

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Speaker 1: some usual pop sigh misinformation along the way. Welcome to

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Speaker 1: Daniel and Kelly's extraordinarily fabulous colorful Universe.

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Speaker 2: Hello, my name is Kelly Windersmith. I study parasites and

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Speaker 2: space and I love looking at the night sky.

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Speaker 1: Hi. I'm Daniel. I'm a particle physicist, and I don't

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Speaker 1: have a favorite color.

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Speaker 2: I do. Mine's purple. Why don't you have a favorite color?

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Speaker 1: I don't get the whole principle of choosing a favorite.

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Speaker 1: Like I like the colors, they're all nice. Why do

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Speaker 1: I have to pick one and say this one's my

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Speaker 1: favorite color? Like, I like purple, it's nice. I like orange. Yellow,

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Speaker 1: it's pretty good too. Blue is so soothing. I like

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Speaker 1: the colors. Grown do you have a favorite child?

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Speaker 2: You know? You and Zach. I'll ask Zach what's your favorite?

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Speaker 2: Blah blah blah, and he's like, I don't see any

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Speaker 2: reason to pick a favorite. And I'm like, because people

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Speaker 2: use this as a conversation starter, and you're a conversation killer.

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Speaker 1: I was just gonna say, it's the way people start conversations.

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Speaker 1: But it feels to me like dishonest, it's false. It's

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Speaker 1: like it's not what you really think or feel. It's

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Speaker 1: just like, oh, you like red, I like green. You

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Speaker 1: know it's not sincere, so it doesn't start a good conversation.

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Speaker 2: I think it's implied that, like, you're not married to

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Speaker 2: that color for the rest of your life. I was

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Speaker 2: doing a book signing. I was like, oh, so tell

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Speaker 2: me something about you. And he's like, I hate small talk.

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Speaker 1: And I was like, oh, okay, and that's the end

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Speaker 1: of this conversation.

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Speaker 2: I did stop talking. I was like, okay, all right,

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Speaker 2: I don't know what else to say. Now you've ruined

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Speaker 2: the question I was planning on asking you today because

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Speaker 2: it involves the word favorite. But I was going to

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Speaker 2: ask you about your favorite or the best star viewing

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Speaker 2: experience you've had, Like when was the moment when the

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Speaker 2: sky was most clear and you could see the farthest.

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Speaker 1: I think one of my favorite observing moments is not

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Speaker 1: actually looking at stars, because you know, stars are hard

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Speaker 1: to make out any features for because they're so far away.

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Speaker 1: They're sicly just points of light. But stuff in our

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Speaker 1: Solar system that you can actually see. And back in

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Speaker 1: the mid nineties, I was working on a project over

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Speaker 1: the summer right when comet shoemaker Levee was about to

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Speaker 1: slam into Jupiter, and I had access to a super

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Speaker 1: high speed camera and so we pointed it at Jupiter

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Speaker 1: hoping to catch really high speed photographs of the impact

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Speaker 1: to see like, you know, planet sized plumes of fire

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Speaker 1: emerging from it. It was super cool.

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Speaker 2: I mean, I do feel like I asked you something

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Speaker 2: like what's your favorite color? And you answered macaroni and cheese.

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Speaker 2: But that is a very cool story. Did you see

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Speaker 2: what you wanted to see?

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Speaker 1: Yeah, we got to see shoemaker levee impact on Jupiter.

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Speaker 1: Unfortunately impacted around the back of Jupiter, so we didn't

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Speaker 1: see the collision itself, but we did see the plume

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Speaker 1: coming up over the limb of Jupiter. Really pretty amazing.

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Speaker 1: I sort of remember it in black and white. I

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Speaker 1: can't really answer your color questions, but Jupiter does have

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Speaker 1: a lot of beautiful colors. See, it doesn't just pick.

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Speaker 2: One that's amazing. And you keep sort of wiggling around

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Speaker 2: my questions. That's fine, that's fine. What you're saying is interesting,

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Speaker 2: so it's fine for content.

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Speaker 1: And i'd ask you what your favorite color is, But

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Speaker 1: you're wearing a color right now. You literally have paint

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Speaker 1: all over your arms. That's your favorite color.

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Speaker 2: Well, that's my favorite color for my laundry room renovation

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Speaker 2: that I'm working on right now. But my favorite star

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Speaker 2: viewing moment I got really lucky one. So I was

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Speaker 2: in Costa Rica and I was in a community where

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Speaker 2: there was a big leather back sea turtle conservation project

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Speaker 2: going on, and leather back sea turtles can get distracted

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Speaker 2: by lights and then they move towards those lights and

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Speaker 2: then they don't go out to the ocean after they

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Speaker 2: hatch like they're supposed to. So the whole community had

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Speaker 2: very dim red lights and they turned off all of

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Speaker 2: their bright lights at night, and so we were sort

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Speaker 2: of in the middle of nowhere and all the lights

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Speaker 2: were off. So my job at two am was to

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Speaker 2: guard the hatchery so that raccoons wouldn't dig up the

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Speaker 2: leather back sea turtle eggs and eat them.

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Speaker 1: Wow.

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Speaker 2: So it was like two am in Costa Rica. It

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Speaker 2: was the middle of nowhere. All the lights were out,

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Speaker 2: and it was just the most amazing view of the

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Speaker 2: Milky Way and you know, shootings stars and at any

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Speaker 2: time there could be baby turtles. Like that's Pete Kelly

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Speaker 2: life right there. I'd much rather spend time with my kids,

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Speaker 2: But that was amazing.

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Speaker 1: That sounds like a magical moment. Did the night sky

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Speaker 1: look anything like your outfit does right now?

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Speaker 2: Yeah, except a fewer holes in it. This is also

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Speaker 2: what I wear. What I'm doing some renovation work. I

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Speaker 2: don't know, it's comfy.

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Speaker 1: For the audio only listeners. Kelly's wearing something which looks

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Speaker 1: like it has star patterns on it.

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Speaker 2: It does. And my daughter has a matching outfit that

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Speaker 2: we wear sometimes, and she still wants to wear even

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Speaker 2: though this dress has holes in it. Whenever she wants

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Speaker 2: to wear a matching outfit, I am all in because

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Speaker 2: I imagine it's like weeks or months before she's too

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Speaker 2: old to want to do that. So every day it's

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Speaker 2: an automatic.

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Speaker 1: Yes, You've got to savor those moments when the kids

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Speaker 1: still want to spend time with you, because pretty soon

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Speaker 1: they're going to grow up and move on.

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Speaker 2: I know, I know your kid's going to college.

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Speaker 1: And kids are not the only thing growing up and

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Speaker 1: changing and moving on. Everything in the universe is going

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Speaker 1: through its own life cycle, including the stars in the sky,

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Speaker 1: burning and glowing and changing colors as they do.

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Speaker 2: Yeah. So when I was listening to your introduction, I

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Speaker 2: was realizing that I don't appreciate all the colors of

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Speaker 2: the stars in the sky. I just think of them

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Speaker 2: as white and sort of look at them as sort

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Speaker 2: of a blurry something. I don't pay attention to the

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Speaker 2: individual colors, the palette of the universe. So I'm excited

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Speaker 2: that next time I look at the night sky, I'll

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Speaker 2: pay a little bit more attention, and I'm excited to

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Speaker 2: learn more from you today.

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Speaker 1: Yeah, the universe is very colorful, but it's not just

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Speaker 1: to please you or to start conversation among two am

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Speaker 1: sky watchers who can otherwise talk to each other. It's

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Speaker 1: for physics reasons, and the colors in the night sky

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Speaker 1: are going to tell us a lot about what's going

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Speaker 1: on inside those.

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Speaker 2: Stars, as long as it's not for chemistry reasons.

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Speaker 1: So this is actually part one of a two part

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Speaker 1: series about why stars have colors and what it tells

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Speaker 1: us about the universe, which ends up with a really

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Speaker 1: interesting story about yet another overlooked female astronomer.

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Speaker 2: Oh I love when I'm surprise. While we're recording, I

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Speaker 2: didn't realize this was a two parter.

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Speaker 1: I just realized as the two parter because I'm preparing

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Speaker 1: that other episode, and now I'm understanding, Oh my gosh,

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Speaker 1: this is the perfect setup for that episode. So good

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Speaker 1: job Daniel realizing that in real time.

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Speaker 2: Welcome to Star Week.

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Speaker 1: This is how carefully we plan the episodes on the podcast.

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Speaker 1: All right, So before we dig deeper, I was curious

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Speaker 1: if people knew why stars had different colors, and so,

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Speaker 1: as usual, I went out to our group of wonderful, clever, hilarious,

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Speaker 1: well informed, good looking volunteers to ask them if you

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Speaker 1: would like to join their ranks for future episodes. Please

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Speaker 1: don't be shy, right to us two questions at Danielankelly

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Speaker 1: dot org. We'll hook you up in the meantime, think

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Speaker 1: about it for yourself. Do you know why stars are

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Speaker 1: different colors? Here's what our volunteers had to say. We

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Speaker 1: know the color here on Earth is based on different

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Speaker 1: wavelengths of light, so I'm assuming that the same principles

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Speaker 1: apply to stars.

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Speaker 3: Red shift the including distance from and speed away from

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Speaker 3: the observer.

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Speaker 4: Color of the stars related to its size. So the

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Speaker 4: older the stars, the more it's been able to fuse,

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Speaker 4: the heavier elements you get different.

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Speaker 1: Spectrum their temperature and the element.

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Speaker 5: I know that big hot stars are described as below

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Speaker 5: and small coola stars described as red, and middlely ones

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Speaker 5: like our sun are yellow.

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Speaker 4: Well, I think the color of stars depends pretty well

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Speaker 4: solely on their age.

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Speaker 3: I think stars are different colors based on the levels

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Speaker 3: of hydrogen and helium in the star.

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Speaker 4: Red ones are shy, and as they get closer they

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Speaker 4: turn red.

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Speaker 1: Blue ones are kind of cool, so they're going away

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Speaker 1: from you. They don't care.

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Speaker 2: Different elements of different colors, and stars throughout their life

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Speaker 2: fuses loads of different elements.

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Speaker 1: I think stars are different colors because of the gases

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Speaker 1: that are in them, and also because of the temperature

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Speaker 1: of the star.

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Speaker 4: Probably due to their composition, different elements they are made

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Speaker 4: up of, and perhaps also their size and perhaps just

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Speaker 4: how they're burning their energy output.

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Speaker 1: Also, the universe believes in diversity, equity inclusion, and that's

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Speaker 1: why they're different colors.

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Speaker 2: The temperatures are different and that causes the black body

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Speaker 2: radiation peaks to be at different wavelength.

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Speaker 4: Stars are different colors because they have different elements and

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Speaker 4: they burn at different temperatures, which changes the color we see.

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Speaker 4: I'm really not sure where the stars are different colors,

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Speaker 4: but if I had to guess, I would say it

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Speaker 4: had to do something with where they were at in

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Speaker 4: their life cycle and the gases that they are made

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Speaker 4: up of.

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Speaker 3: I think stars are different colors because the way they

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Speaker 3: expand and like the gases inside of them like as

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Speaker 3: they expand and get hotter, I think they like change

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Speaker 3: colors and stay those colors their lifetime.

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Speaker 1: I would think that stars are different colors because they

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Speaker 1: emit different light particles, but I think a nonscience the

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Speaker 1: answer would be that they have a cool aura.

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Speaker 2: Amazing answers I chuckled, and some really clever insights here.

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Speaker 2: What did you think, Daniel?

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Speaker 1: I think there's a lot of interesting stuff going on here.

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Speaker 1: The picture I'm putting together of what people imagine causes

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Speaker 1: the different colors of stars is that this different fusion

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Speaker 1: happening with like different ingredients. Maybe you have more metal

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Speaker 1: here and more metal there, and that's somehow changing what's

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Speaker 1: going on, and that's changing the burning of the star

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Speaker 1: the way you can put copper in a Bunsen burner

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Speaker 1: and it turns green, for example.

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Speaker 2: That is my understanding coming into this conversation is that

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Speaker 2: I do think it depends on what elements are getting

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Speaker 2: burned and how hot. But often I'm wrong.

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Speaker 1: So I suspect a lot of you listening out there

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Speaker 1: probably think the same thing, which is why we do

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Speaker 1: this segment to orient us and understand where we need

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Speaker 1: to take you from your current understanding to a deeper,

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Speaker 1: more physical understanding. So we hope that by the end

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Speaker 1: of the episode you have a deeper view of why

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Speaker 1: stars have different colors, because the answer is a little

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Speaker 1: bit more subtle than anything we heard from our volunteers.

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Speaker 2: All Right, I love it. Let's dig in and let's

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Speaker 2: start with the basics. Tell me about light and color.

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Speaker 1: Right, So some of the listeners commented that different colors

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Speaker 1: mean different wavelengths, and that's true. Of course we're interested

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Speaker 1: in like why is flight emitted at different wavelengths? But

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Speaker 1: fundamentally it's important to understand the physical mechanism here, like

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Speaker 1: why are we seeing different colors? And they're right, because

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Speaker 1: light is electromagnetic radiation. The universe is filled with electromagnetic field,

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Speaker 1: and that field can ripple, and when electrons in alpha

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Speaker 1: centauri wiggle, they cause ripples in that field because electrons

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Speaker 1: are connected to that field. Right, When electron moves, it

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Speaker 1: wiggles that field, and that wiggle is what we see

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Speaker 1: as photons, for example. And those wiggles have frequencies, and

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Speaker 1: the frequencies correspond to different wavelengths, and those wavelengths correspond

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Speaker 1: to colors.

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Speaker 2: I feel like a bunch of pieces actually just click

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Speaker 2: together in my head that should have clicked together much earlier,

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Speaker 2: but there they are, okay.

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Speaker 1: Click And the same mechanism is like how radio works

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Speaker 1: wizer an antenna because electrons are going up and down

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Speaker 1: in the antenna, and as they do so, they make

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Speaker 1: the photon field wiggle just the same way, like if

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Speaker 1: you're holding the end of a jump rope and you

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Speaker 1: go up and down, you make wiggles down the jump rope.

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Speaker 1: It's exactly the same mechanism.

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Speaker 2: I think the piece is just unclicked. Oh no, I

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Speaker 2: think I don't understand the electrons going up and down

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Speaker 2: the antenna. Thing is it just radio waves are traveling

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Speaker 2: through the antenna and that's radio frequencies.

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Speaker 1: Well, an electron has an electric field around it, right,

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Speaker 1: If the electron just sits there, the electric field doesn't change.

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Speaker 1: What happens if the electron moves up, well, the electric

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Speaker 1: field also has to move up. Or if the electron

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Speaker 1: field moves up and then down, the electric field moves

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Speaker 1: up and then down. But it doesn't do so instantly,

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Speaker 1: Like if you wiggle an electron in an antenna that's

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Speaker 1: a mile away from me, I don't instantly see it

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Speaker 1: change in the electric field. It has to propagate and

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Speaker 1: So if the electron is going constantly up and down

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Speaker 1: and up and down, then it's making waves up and

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Speaker 1: down in the electric field that propagate out away from it.

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Speaker 1: And if I'm a mile away and i have electrons

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Speaker 1: in my antenna, those wiggles in the electric field are

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Speaker 1: going to push on my antenna's electrons, which are going

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Speaker 1: to go up and down, and then I'm going to

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Speaker 1: read that out as current. So yeah, the electrons in

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Speaker 1: descending antenna wiggle the electric field, which wiggles. Electrons in

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Speaker 1: the receiving antenna, which move and can be picked up

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Speaker 1: by my electronics can be reclick yep, yah yah. And

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Speaker 1: so the different colors are different wavelengths of those wiggles.

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Speaker 1: Photons are wiggles in the electromagnetic field, but they can

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Speaker 1: have different wavelengths. Right. They can be really really narrow,

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Speaker 1: so they're like very high frequency, like ultraviolet or purple.

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Speaker 1: They can be really really long, so they're like radio

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Speaker 1: waves or red light or infrared light. And there's a

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Speaker 1: potential source of confusion here. Remember these things are quantum mechanicals,

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Speaker 1: So photons are discrete units. Like you can have one

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Speaker 1: photon or two photons, but you can't have two point

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Speaker 1: seven eighty one photons, but you can have photons of

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Speaker 1: any energy. That's a continuous spectrum, So there's an infinite

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Speaker 1: number of frequencies on the spectrum.

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Speaker 2: So does that mean there's an infinite number of colors?

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Speaker 1: Mmmm, yes, great question. Right, So there are an infinite

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Speaker 1: number of frequency choices for a photon. But colors are

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Speaker 1: things that we experience in our mind. Right. There are

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Speaker 1: responds to signals on the optic nerve. So let's talk

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Speaker 1: momentarily about the physics of the biology of what's going

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Speaker 1: on there. You have photons that enter your eyeball and

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Speaker 1: they hit the back of the eyeball and the back

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Speaker 1: of the eyeball, there are three different kinds of cells

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Speaker 1: that respond to different colors. They have proteins on them

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Speaker 1: that operate like little switches, and when they absorb a

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Speaker 1: photon of the right color, they flip that switch and

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Speaker 1: they send a signal up the optic nerve. This whole

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Speaker 1: continuous spectrum of photons gets converted into three numbers, how

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Speaker 1: much did you turn on cone one, Cone two, and

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Speaker 1: cone three? And then your brain interprets those and generates

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Speaker 1: the experience of the color. So the color is actually

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Speaker 1: in your mind. It's not on the photon, right, we

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Speaker 1: say red photon or green photon when we're being sloppy,

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Speaker 1: but really the boon has an energy and the experience

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Speaker 1: of color is only in your brain.

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Speaker 2: And we got a great question on our discord channel,

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Speaker 2: which you can join by going over to Danielankelly dot

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Speaker 2: org and clicking the invite and Quicksilver the DIRG Sorr

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Speaker 2: who was the discord quicksilver the DIRG anyway, this individual

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Speaker 2: going by the moniker Quicksilver, the DIRG wanted to know

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Speaker 2: something about why we see the colors that we do see.

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Speaker 2: And actually, our distant ancestors had two kinds of light

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Speaker 2: cones and we have three, and so why do we

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Speaker 2: see the colors that we see. The answer, really, at

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Speaker 2: the end of the day is we're not one hundred

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Speaker 2: percent sure, but we think what happens is that there

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Speaker 2: was a gene duplication event, and these happens every once

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Speaker 2: in a while in our genome. And so now instead

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Speaker 2: of having two different kinds of cones, you had two

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Speaker 2: different kinds of cones, but three different genes for those cones,

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Speaker 2: and over time selection tinkered with that extra new gene

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Speaker 2: and we ended up with the ability to see the

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Speaker 2: color red. Already see things like green, and the thought

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Speaker 2: was that seeing colors like red allowed our primate ancestors

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Speaker 2: to differentiate between different kinds of fruits and in particular

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Speaker 2: whether or not the fruits were ripe. And there are

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Speaker 2: some macaques that only have two types of cones and

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Speaker 2: some macaques that have three types of cones in the

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Speaker 2: same species, there's this variability. Some studies have found that

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Speaker 2: if you have three types of cones, you get ripe

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Speaker 2: fruits quicker and eat them quicker, which shows a benefit.

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Speaker 2: But other studies and other kinds of macaques haven't found

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Speaker 2: that because it's biology, so it depends depends there you go.

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Speaker 1: And I think you put your finger on it, because

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Speaker 1: the important thing here is the ability to distinguish different colors, right,

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Speaker 1: But I think that depends not just on like the

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Speaker 1: number of different kinds of cones you have, but also

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Speaker 1: the processing power behind it. I know that like mantis,

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Speaker 1: shrimp are famous for having like more than ten different

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Speaker 1: kinds of cones, but they actually apparently are terrible at

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Speaker 1: distinguishing different colors because they have almost no neural processing

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Speaker 1: behind it. I think they might just like experience ten

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Speaker 1: different literal colors. We have a huge number of different

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Speaker 1: colors that we can distinguish because we can do this interpolation, right,

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Speaker 1: That's what your brain is doing is it's getting like, oh,

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Speaker 1: a little bit from the bluish cone, a little bit

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Speaker 1: from the reddish cone, a little bit from the greenish cone,

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Speaker 1: and it's saying, okay, what color would give me this

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Speaker 1: pattern and then sort of inferring what color might be there.

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Speaker 1: But again, the experience of color, the reason like red

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Speaker 1: is reddish and blue is bluish has nothing to do

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Speaker 1: with the photon. That's something your brain has assigned to

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Speaker 1: it has invented, has fabricated. Right in principle, it could

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Speaker 1: make up a new color. If you've got a new

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Speaker 1: cone and planted that was sensitive to the ultraviolet, that

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Speaker 1: your brain could invent a new experience, not one that's

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Speaker 1: a combination of the other ones, but like a real

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Speaker 1: novel experience to represent the signal from the UV cone.

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Speaker 2: And there are insects that can see in the UV.

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Speaker 2: And it makes me so sad when I look at

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Speaker 2: a beautiful flower and think there's layers that I'm missing.

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Speaker 2: But anyway, I'm guessing based on our examples that you

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Speaker 2: and I both read An Immense World by Ed Young,

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Speaker 2: because we both seem to have cherry picked examples from

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Speaker 2: that fantastic book.

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Speaker 1: It is definitely a great book, a lot of fun,

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Speaker 1: and recommend everybody read that, especially if you're interested in

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Speaker 1: physics and biology, because it covers both of those topics

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Speaker 1: about our experience.

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Speaker 2: Okay, so the three kind of cones that we have

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Speaker 2: determine what colors we can see in the night sky.

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Speaker 2: Are we missing a lot or are there ultraviolet stars

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Speaker 2: out there that we're missing.

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Speaker 1: We're definitely missing a lot because we can only see

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Speaker 1: a certain range of photons ultraviolet and infrared. Everything below

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Speaker 1: that and everything above that we can't see, and the

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Speaker 1: sky definitely is bright in those colors. That's why, for example,

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Speaker 1: we have radio telescopes and infrared telescopes and ultraviolet telescopes

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Speaker 1: because stars and other different phenomena emit differently in those

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Speaker 1: spectrum and if you can see those, you can see

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Speaker 1: different kinds of things. Also, the universe is transparent differently

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Speaker 1: in different frequencies. Some frequencies of life can go through

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Speaker 1: dust clouds and others can't, and so if you want

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Speaker 1: to see through dust clouds, you've got to change your frequency.

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Speaker 1: So absolutely the night sky looks very different outside the

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Speaker 1: visible range our star, and of course peaks right in

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Speaker 1: the center of the visible range, which again is no coincidence. Right.

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Speaker 1: If you're going to evolve vision, you might as well

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Speaker 1: evolve it to be able to see the most common

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Speaker 1: photons that are around you. So if we had evolved

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Speaker 1: around a redder star, for example, probably our visible range

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Speaker 1: would be lower. The Sun is an unusual star. Most

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Speaker 1: of the stars out there are redder than our star.

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Speaker 1: Our star is yellower than most stars out there, so

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Speaker 1: we may have a different visual range than most of

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Speaker 1: the aliens.

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Speaker 2: So are you postulating that the color of the star

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Speaker 2: determines the colors that we see, because I feel like

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Speaker 2: that's not an evolutionary argument that I understand. Does the

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Speaker 2: color of our star impact the color of things on

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Speaker 2: Earth that are important for food, mating or running away

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Speaker 2: from a predator?

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Speaker 1: I think it makes sense for us to be most

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Speaker 1: sensitive to the photons that are most present here on

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Speaker 1: Earth for that range. Whether we can experience two or

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Speaker 1: seven or three or whatever, I think is a different question.

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Speaker 1: But for us to be sensitive to the most common

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Speaker 1: kind of photons makes sense to me. I'll give you

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Speaker 1: that you're skeptical. Why A you're skeptical?

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Speaker 2: So I totally follow the argument that the most common

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Speaker 2: kinds of photons in the environment would be the ones

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Speaker 2: that were good to sense. But if for some reason

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Speaker 2: those didn't translate into an increased ability to find your

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Speaker 2: food or an increased ability to recognize a mate, then

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Speaker 2: I don't necessarily think that selection would hone in on those.

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Speaker 2: And there's so much variability and what animals can see.

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Speaker 2: You know, there's plenty of dichromates, so they don't have

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Speaker 2: three kinds of cones and they get along just fine.

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Speaker 2: So yeah, how do you explain the variability?

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Speaker 1: Then that's a great point. And I can give you

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Speaker 1: an example to support your point, which is neutrinos. Neutrinos

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Speaker 1: are everywhere in our environment, but pretty much useless because

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Speaker 1: everything is transparent to them, and so it wouldn't be

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Speaker 1: great to develop a neutrino eyeball even though they're everywhere.

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Speaker 1: So you're right, just being ubiquitous isn't enough to have

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Speaker 1: to be useful. And so I think the combination of

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Speaker 1: the fact that they are everywhere, and stuff on Earth

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Speaker 1: tends to not be transparent to them, makes them useful

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Speaker 1: for us to see things. So I think you're right.

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Speaker 1: It's more complicated than just the physics of this region

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Speaker 1: has to also be like useful in your environment. For sure.

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Speaker 1: I have no idea why you would have two or

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Speaker 1: seven cones.

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Speaker 2: I guess both of our fields are useful. You ponder

439
00:21:14,800 --> 00:21:17,400
Speaker 2: the question Daniel and I were just debating during the break,

440
00:21:17,440 --> 00:21:19,840
Speaker 2: And when we get back, we'll talk about why stars

441
00:21:19,880 --> 00:21:39,160
Speaker 2: have different colors? All right, and we're back. You look

442
00:21:39,240 --> 00:21:41,159
Speaker 2: up at the night sky and there are lots of

443
00:21:41,160 --> 00:21:43,560
Speaker 2: different colors of stars. Though I'll be honest, I missed

444
00:21:43,600 --> 00:21:45,880
Speaker 2: that in the past. I'm gonna be paying much more

445
00:21:45,880 --> 00:21:49,879
Speaker 2: attention now. So Daniel, why do those stars have different colors?

446
00:21:50,200 --> 00:21:53,000
Speaker 1: So there's sort of three big factors that control what

447
00:21:53,080 --> 00:21:56,199
Speaker 1: color a star is in our sky. One is what

448
00:21:56,359 --> 00:21:59,879
Speaker 1: it's made out of, another one is its temperature, and

449
00:22:00,160 --> 00:22:02,680
Speaker 1: the last one is its velocity. So let's do those

450
00:22:02,720 --> 00:22:05,000
Speaker 1: in order. What it's made out of. This is the

451
00:22:05,000 --> 00:22:07,399
Speaker 1: one that's connected to your experience of like putting copper

452
00:22:07,400 --> 00:22:10,280
Speaker 1: in a Bunsen burner and seeing it glow green. That's

453
00:22:10,320 --> 00:22:13,840
Speaker 1: because atoms are quantum mechanical little objects and they have

454
00:22:14,000 --> 00:22:17,359
Speaker 1: energy levels. You know, electrons around an atom can't just

455
00:22:17,400 --> 00:22:19,639
Speaker 1: be at any energy willy nilly. There's a ladder of

456
00:22:19,760 --> 00:22:22,800
Speaker 1: energies there, and because there's a ladder of energies there,

457
00:22:22,960 --> 00:22:26,159
Speaker 1: they can only eat and emit photons of certain energies,

458
00:22:26,200 --> 00:22:28,560
Speaker 1: the ones that let them go up or down the ladder.

459
00:22:28,720 --> 00:22:30,639
Speaker 1: So when an electron is around an atom and a

460
00:22:30,640 --> 00:22:34,200
Speaker 1: photon comes by, if that photon has just the right

461
00:22:34,320 --> 00:22:36,440
Speaker 1: energy to take it up one or two or seven

462
00:22:36,600 --> 00:22:39,240
Speaker 1: rungs on that ladder, it can eat that photon. You

463
00:22:39,280 --> 00:22:42,040
Speaker 1: might think I don't care about what photons the electron eats,

464
00:22:42,200 --> 00:22:45,200
Speaker 1: but actually does matter what it absorbs and what it reflects,

465
00:22:45,240 --> 00:22:48,000
Speaker 1: because what it reflects is what you see. Right, If

466
00:22:48,000 --> 00:22:50,800
Speaker 1: you're looking at something that's blue, it's not blue because

467
00:22:50,840 --> 00:22:54,160
Speaker 1: it's eating blue photons. It's blue because it's eating everything

468
00:22:54,200 --> 00:22:57,919
Speaker 1: but the blue photons. It's reflecting blue photons back at you.

469
00:22:58,440 --> 00:23:01,159
Speaker 1: Remember you see something blue because some light in the

470
00:23:01,200 --> 00:23:05,040
Speaker 1: blue range has hit your eyeball and you responded to that.

471
00:23:05,400 --> 00:23:08,720
Speaker 1: So it's important what energy levels an atom can absorb.

472
00:23:09,160 --> 00:23:11,960
Speaker 1: And the same is true also in the reverse, Adam's

473
00:23:11,960 --> 00:23:13,879
Speaker 1: in midlight. That's what's happening to the copper in your

474
00:23:13,920 --> 00:23:17,359
Speaker 1: Bunsen burner. It's getting hot, and the inverse process is happening.

475
00:23:17,400 --> 00:23:20,440
Speaker 1: An electron jumps down energy levels and gives off a photon,

476
00:23:20,480 --> 00:23:22,600
Speaker 1: a green photon in the case of copper.

477
00:23:22,840 --> 00:23:26,280
Speaker 2: That always felt very counterintuitive to me, that the color

478
00:23:26,359 --> 00:23:28,880
Speaker 2: that I'm seeing is the color that's being given off

479
00:23:28,960 --> 00:23:32,120
Speaker 2: by something. It almost feels like everything is disguising itself

480
00:23:32,200 --> 00:23:34,199
Speaker 2: in some way. I don't I don't know why my

481
00:23:34,240 --> 00:23:36,040
Speaker 2: brain ahead trouble wrapping itself around that.

482
00:23:36,320 --> 00:23:38,840
Speaker 1: I totally remember the first time I understood that. I

483
00:23:38,880 --> 00:23:41,080
Speaker 1: was like nine, and I was like, oh my gosh,

484
00:23:41,200 --> 00:23:43,600
Speaker 1: things that are blue are not actually blue, they just

485
00:23:43,720 --> 00:23:46,320
Speaker 1: look blue. And then I realized, well, maybe that's what

486
00:23:46,320 --> 00:23:48,720
Speaker 1: it means to be blue, to look blue. But yeah,

487
00:23:48,720 --> 00:23:50,760
Speaker 1: I had the sense that like, if I could see

488
00:23:50,840 --> 00:23:54,159
Speaker 1: through these photons to what things actually looked like, I

489
00:23:54,200 --> 00:23:56,560
Speaker 1: could perceive a deeper truth to the universe. But the

490
00:23:56,600 --> 00:23:58,520
Speaker 1: universe is kind of a construct we've assembled in our

491
00:23:58,560 --> 00:24:01,160
Speaker 1: head from our experience of it, and there's a lot

492
00:24:01,200 --> 00:24:04,600
Speaker 1: of that that's imagined, that's put together from our experience

493
00:24:04,600 --> 00:24:07,000
Speaker 1: and the way we paint these colors on things is

494
00:24:07,119 --> 00:24:08,440
Speaker 1: just one layer of that.

495
00:24:08,840 --> 00:24:14,800
Speaker 2: Yeah, man, Yeah, I totally agree though.

496
00:24:15,080 --> 00:24:17,800
Speaker 1: Yeah, but that's the joy physics. It helps you separate

497
00:24:17,840 --> 00:24:19,720
Speaker 1: what's really out there and what you know about it,

498
00:24:19,760 --> 00:24:22,040
Speaker 1: which you don't know about it, which parts you're building

499
00:24:22,080 --> 00:24:25,480
Speaker 1: in your mind. Super fascinating, even if it is philosophical

500
00:24:25,520 --> 00:24:27,879
Speaker 1: and could never be understood. So the next piece to

501
00:24:27,960 --> 00:24:30,880
Speaker 1: understand is why things have different colors? Right, We said

502
00:24:30,920 --> 00:24:34,520
Speaker 1: that atoms have energy levels, and electrons can jump up

503
00:24:34,680 --> 00:24:38,320
Speaker 1: energy levels eating photons or down energy levels emitting photons,

504
00:24:38,720 --> 00:24:42,520
Speaker 1: and those photons have specific energies corresponding to those gaps. Well,

505
00:24:42,560 --> 00:24:46,560
Speaker 1: different atoms have different energy levels. Copper and mercury and

506
00:24:46,640 --> 00:24:50,280
Speaker 1: helium and hydrogen all have different energy levels. Because the

507
00:24:50,359 --> 00:24:52,800
Speaker 1: solutions to the Shorteninger equation are different, you got different

508
00:24:52,840 --> 00:24:55,639
Speaker 1: numbers of protons, and the whole configuration of the atom

509
00:24:55,720 --> 00:24:58,440
Speaker 1: is different. Every atom has its own unique ladder, which

510
00:24:58,560 --> 00:25:01,080
Speaker 1: means that they have like a fingerp If you take

511
00:25:01,080 --> 00:25:02,800
Speaker 1: an element and you take a gas of it and

512
00:25:02,880 --> 00:25:04,960
Speaker 1: heat it up, and then you take the light from

513
00:25:04,960 --> 00:25:07,479
Speaker 1: that pass it through a prism to spread it out,

514
00:25:07,680 --> 00:25:11,000
Speaker 1: you'll see that Each element has its own unique fingerprint,

515
00:25:11,240 --> 00:25:14,359
Speaker 1: its own spectrum. They'll have these little bands like a

516
00:25:14,400 --> 00:25:16,439
Speaker 1: blue one and a red one, or a different element

517
00:25:16,560 --> 00:25:18,360
Speaker 1: will have like a green band and the blue band

518
00:25:18,359 --> 00:25:21,080
Speaker 1: will be shifted over. So you can tell what something

519
00:25:21,119 --> 00:25:23,320
Speaker 1: is made out of just by looking at a spectrum

520
00:25:23,359 --> 00:25:25,439
Speaker 1: of a hot gas. So there's two things that are

521
00:25:25,440 --> 00:25:29,240
Speaker 1: happening here. You have hot gas, it glows in certain colors, right,

522
00:25:29,359 --> 00:25:31,520
Speaker 1: And if you have more oxygen, you glow in these colors.

523
00:25:31,600 --> 00:25:33,639
Speaker 1: You have more neon, you glow in those colors. And

524
00:25:33,800 --> 00:25:35,760
Speaker 1: our whole next episode is going to be about using

525
00:25:35,760 --> 00:25:38,960
Speaker 1: spectroscopy to understand what stars are made out of. But

526
00:25:39,000 --> 00:25:42,359
Speaker 1: this also absorption, Right, if a star has an atmosphere

527
00:25:42,400 --> 00:25:45,360
Speaker 1: and that atmosphere is mostly neon, for example, then it's

528
00:25:45,359 --> 00:25:48,240
Speaker 1: going to absorb that light. So if you have a

529
00:25:48,240 --> 00:25:50,960
Speaker 1: hot blob of gas, it emits light to those frequencies.

530
00:25:51,119 --> 00:25:54,719
Speaker 1: If you have light that passes through an atmosphere, then

531
00:25:54,720 --> 00:25:56,520
Speaker 1: it absorbs those frequencies.

532
00:25:57,040 --> 00:26:00,159
Speaker 2: So it feels to me now like we have an

533
00:26:00,200 --> 00:26:03,720
Speaker 2: infinite number of combinations of elements that could be emitting

534
00:26:03,880 --> 00:26:06,479
Speaker 2: and like gases that could be absorbing. How do we

535
00:26:06,520 --> 00:26:09,000
Speaker 2: make sense of the output given that there's now so

536
00:26:09,080 --> 00:26:11,800
Speaker 2: many different options, and it's probably not just one element

537
00:26:11,840 --> 00:26:13,760
Speaker 2: that's emitting at a time. There's probably a couple different

538
00:26:13,760 --> 00:26:15,919
Speaker 2: things that are emitting. And I'm overwhelmed.

539
00:26:16,080 --> 00:26:18,639
Speaker 1: Yes, it is overwhelming. It's a hard problem, and it

540
00:26:18,680 --> 00:26:20,879
Speaker 1: was solved by a very clever young lady around the

541
00:26:20,880 --> 00:26:22,240
Speaker 1: turn of the century. And we're going to talk about

542
00:26:22,280 --> 00:26:24,600
Speaker 1: that in the next episode. Okay, but even if you

543
00:26:24,680 --> 00:26:27,199
Speaker 1: mix all these elements together, what you get are a

544
00:26:27,240 --> 00:26:30,400
Speaker 1: bunch of different spikes Like these are narrow emission lines.

545
00:26:30,440 --> 00:26:32,560
Speaker 1: You can't put them together to get a broad spectrum.

546
00:26:32,600 --> 00:26:34,200
Speaker 1: And that's not what most of the light from the

547
00:26:34,240 --> 00:26:37,560
Speaker 1: stars is. This is like people's conception, but most of

548
00:26:37,560 --> 00:26:40,160
Speaker 1: the light from the star comes from a completely different process.

549
00:26:40,200 --> 00:26:44,200
Speaker 1: It's not from atomic emission and absorption. It comes from

550
00:26:44,240 --> 00:26:47,919
Speaker 1: the plasma inside the star just glowing at a certain temperature.

551
00:26:48,080 --> 00:26:51,760
Speaker 2: What all right, we were all wrong, audience and friends

552
00:26:51,760 --> 00:26:53,960
Speaker 2: of mine. Okay, so Daniel, let's move on to the

553
00:26:54,000 --> 00:26:55,840
Speaker 2: next thing. Then tell us more about this thing that

554
00:26:55,880 --> 00:26:57,359
Speaker 2: actually contributes most of the color.

555
00:26:57,720 --> 00:26:59,840
Speaker 1: Yeah, so we said that the color of stars comes

556
00:26:59,840 --> 00:27:01,760
Speaker 1: from what they're made out of, and that has to

557
00:27:01,760 --> 00:27:04,560
Speaker 1: do with atomic absorption, and emission mostly in the atmosphere

558
00:27:04,600 --> 00:27:07,720
Speaker 1: of stars, but also from its temperature. And so that's

559
00:27:07,720 --> 00:27:09,560
Speaker 1: what we're going to dig into next. And there's a

560
00:27:09,600 --> 00:27:13,200
Speaker 1: process here that has a terrible, absolutely, terrible, very misleading name.

561
00:27:13,200 --> 00:27:17,080
Speaker 1: It's called black body radiation that describes why stars glow

562
00:27:17,119 --> 00:27:19,679
Speaker 1: at certain temperatures. And it's terribly the name because a

563
00:27:19,720 --> 00:27:22,080
Speaker 1: star doesn't seem like a black body. Right.

564
00:27:22,440 --> 00:27:23,560
Speaker 2: Nope, you guys did it again.

565
00:27:23,800 --> 00:27:26,359
Speaker 1: But in physics, we have a model of some hypothetical

566
00:27:26,440 --> 00:27:29,640
Speaker 1: object with no reflection, Like any photon you shoot at

567
00:27:29,640 --> 00:27:32,040
Speaker 1: it, it will absorb it and just like heat up. And

568
00:27:32,200 --> 00:27:34,919
Speaker 1: even in the hypothetical version, it's not black. It just

569
00:27:34,960 --> 00:27:38,560
Speaker 1: means that it doesn't reflect. It glows because of its temperature.

570
00:27:38,760 --> 00:27:41,240
Speaker 1: Everything in the universe that has a temperature and is

571
00:27:41,280 --> 00:27:43,919
Speaker 1: made of charged particles will glow. Like if you have

572
00:27:43,960 --> 00:27:46,640
Speaker 1: fluorescent lights in your ceiling, you look up that has

573
00:27:46,640 --> 00:27:49,520
Speaker 1: a hot gas in it that's glowing because of its temperature.

574
00:27:49,880 --> 00:27:53,240
Speaker 1: Or you're glowing right now, Kelly, because of your temperature.

575
00:27:53,480 --> 00:27:55,720
Speaker 1: Not in the visible light, but if I put on

576
00:27:55,840 --> 00:27:58,440
Speaker 1: night vision goggles or infrared goggles, I would be able

577
00:27:58,480 --> 00:27:59,880
Speaker 1: to see you emitting light.

578
00:28:00,160 --> 00:28:02,800
Speaker 2: What is the physics definition of glow is it just

579
00:28:02,880 --> 00:28:04,439
Speaker 2: releasing photons or something.

580
00:28:04,760 --> 00:28:08,040
Speaker 1: It's just releasing photons because you have charge particles in you,

581
00:28:08,119 --> 00:28:11,200
Speaker 1: and charge particles are always interacting and moving around and whizzing,

582
00:28:11,200 --> 00:28:14,000
Speaker 1: and when they do so, they emit photons. Like an

583
00:28:14,000 --> 00:28:18,320
Speaker 1: electron can't change directions without emitting a photon. That's how

584
00:28:18,359 --> 00:28:20,359
Speaker 1: it does it. And an electron is flying to the

585
00:28:20,400 --> 00:28:22,720
Speaker 1: universe and it wants to curve along a magnetic fields

586
00:28:22,800 --> 00:28:24,760
Speaker 1: or something, it's got to push out a photon in

587
00:28:24,800 --> 00:28:27,800
Speaker 1: the other direction to conserve momentum. Now you have a

588
00:28:27,840 --> 00:28:30,840
Speaker 1: big blob of gas with all sorts of charge particles

589
00:28:30,880 --> 00:28:33,840
Speaker 1: whizzing around, they're going to be constantly emitting photons, and

590
00:28:33,880 --> 00:28:36,520
Speaker 1: they emit a very broad spectrum. Not like the atoms

591
00:28:36,520 --> 00:28:39,320
Speaker 1: we talked about, we have very specific energy levels. This

592
00:28:39,400 --> 00:28:42,040
Speaker 1: black body radiation is a very broad spectrum, but it

593
00:28:42,040 --> 00:28:44,680
Speaker 1: has a peak that depends on the temperature. So really

594
00:28:44,720 --> 00:28:47,600
Speaker 1: cold things tend to emit in the infrared. Warmer things

595
00:28:47,600 --> 00:28:51,040
Speaker 1: emit invisible. So for example, you take a piece of metal,

596
00:28:51,360 --> 00:28:54,000
Speaker 1: it's glowing right now, even if it's cold, just in

597
00:28:54,040 --> 00:28:56,560
Speaker 1: the infrared. You can't see it. Put in the oven,

598
00:28:56,640 --> 00:28:58,480
Speaker 1: heated up, put it in the forge. It starts to

599
00:28:58,480 --> 00:29:01,680
Speaker 1: glow red, and then it glows white. Right. White? Hot

600
00:29:01,800 --> 00:29:04,360
Speaker 1: is very hot? Why because now it's hot enough to

601
00:29:04,400 --> 00:29:07,560
Speaker 1: be glowing in the visible Keep heating it up. It'll

602
00:29:07,560 --> 00:29:09,600
Speaker 1: start to glow in the ultra violet. You won't see

603
00:29:09,600 --> 00:29:12,160
Speaker 1: it anymore, but it be super duper hot. The temperature

604
00:29:12,160 --> 00:29:15,400
Speaker 1: of something determines the peak of its emission, right, So

605
00:29:15,520 --> 00:29:18,160
Speaker 1: everything in the universe that's made of charge particles glows

606
00:29:18,160 --> 00:29:21,560
Speaker 1: at a certain temperature, and that temperature controls the frequency

607
00:29:21,720 --> 00:29:22,680
Speaker 1: of the emission.

608
00:29:23,000 --> 00:29:25,760
Speaker 2: Okay, all right, a few questions. So when an electron

609
00:29:25,920 --> 00:29:28,240
Speaker 2: kicks out a photon, is it still an electron?

610
00:29:28,400 --> 00:29:30,840
Speaker 1: It's still an electron because a photon is neutral. Yeah.

611
00:29:30,920 --> 00:29:33,200
Speaker 2: How many photons can an electron kick out? Can I

612
00:29:33,240 --> 00:29:34,440
Speaker 2: just do that all the time?

613
00:29:36,600 --> 00:29:39,520
Speaker 1: Oh my gosh, what an amazing question. It makes me

614
00:29:39,560 --> 00:29:41,160
Speaker 1: think of an electron as like having a bag of

615
00:29:41,160 --> 00:29:43,800
Speaker 1: photons that they could run out of, right, like fuel

616
00:29:44,040 --> 00:29:47,600
Speaker 1: You think of like rockets, right, and they need some source. No,

617
00:29:47,680 --> 00:29:50,560
Speaker 1: an electron has an infinite number of photons. Remember, these

618
00:29:50,560 --> 00:29:53,520
Speaker 1: are just wiggles in the electromagnetic field, right, And so

619
00:29:53,920 --> 00:29:57,000
Speaker 1: it's not like it's kicking off some substance. But in

620
00:29:57,080 --> 00:29:59,640
Speaker 1: order to conserve momentum, you have to have some momentum

621
00:29:59,680 --> 00:30:02,479
Speaker 1: move to the ectromagnetic field and some momentum moves through

622
00:30:02,480 --> 00:30:03,520
Speaker 1: the electron field.

623
00:30:03,760 --> 00:30:06,680
Speaker 2: Wow, okay, all right. So say you've got some iron,

624
00:30:07,360 --> 00:30:12,200
Speaker 2: and we talked about iron having emission line spectrums where

625
00:30:12,520 --> 00:30:15,840
Speaker 2: the electrons get excited and they jump to different levels

626
00:30:15,880 --> 00:30:19,200
Speaker 2: and they emit light and then you hate that iron

627
00:30:19,280 --> 00:30:21,960
Speaker 2: up and now it's glowing. Are you saying that the

628
00:30:22,680 --> 00:30:27,680
Speaker 2: glow is more important than the jumping of the levels.

629
00:30:28,240 --> 00:30:31,120
Speaker 1: The most general answer is that it depends on what

630
00:30:31,200 --> 00:30:33,040
Speaker 1: it's made out of and its temperature, and in the

631
00:30:33,040 --> 00:30:36,760
Speaker 1: case of stars, it's mostly black body radiation. Like when

632
00:30:36,760 --> 00:30:39,080
Speaker 1: we look at the spectrum from the Sun, it's almost

633
00:30:39,120 --> 00:30:42,800
Speaker 1: all black body radiation. So that's definitely the most important effect.

634
00:30:43,240 --> 00:30:45,160
Speaker 1: And there's a combination of the two things. So you

635
00:30:45,280 --> 00:30:48,640
Speaker 1: have the star which is glowing very broad spectrum which

636
00:30:48,640 --> 00:30:50,560
Speaker 1: peaks right in the middle of our visual spectrum for

637
00:30:50,640 --> 00:30:53,600
Speaker 1: our star. But then the sun has an atmosphere, and

638
00:30:53,600 --> 00:30:56,720
Speaker 1: this atmosphere is gas and it's made out of various stuff,

639
00:30:56,960 --> 00:31:00,360
Speaker 1: and that atmosphere will eat that spectrum. So the light

640
00:31:00,400 --> 00:31:02,840
Speaker 1: we get from the Sun is a huge black body

641
00:31:02,880 --> 00:31:07,480
Speaker 1: peak with a few lines removed. That's absorption spectrum. So

642
00:31:07,560 --> 00:31:09,600
Speaker 1: if you look at the spectrum from the sun, you

643
00:31:09,680 --> 00:31:12,160
Speaker 1: see reds and yellows and greens and blues, but then

644
00:31:12,200 --> 00:31:14,680
Speaker 1: you see these black spots, these things that have been removed.

645
00:31:15,000 --> 00:31:17,240
Speaker 1: That tells you what's in the atmosphere of the Sun.

646
00:31:17,280 --> 00:31:19,200
Speaker 1: You can see the hydrogen lines have been removed, the

647
00:31:19,200 --> 00:31:21,960
Speaker 1: sodium lines, the helium lines, the magnesium lines, and so

648
00:31:22,000 --> 00:31:24,280
Speaker 1: that helps you figure out what's in the atmosphere of

649
00:31:24,280 --> 00:31:26,800
Speaker 1: the Sun. So the two things happening there is the

650
00:31:26,800 --> 00:31:29,600
Speaker 1: broad glow inside the sun, which we're not fully seeing

651
00:31:29,640 --> 00:31:32,240
Speaker 1: because parts of it have been removed as the Sun's

652
00:31:32,280 --> 00:31:34,880
Speaker 1: atmosphere eats some of those frequencies.

653
00:31:35,080 --> 00:31:35,840
Speaker 2: That's amazing.

654
00:31:36,120 --> 00:31:38,640
Speaker 1: Yeah, and so the last piece we talked about for

655
00:31:38,720 --> 00:31:41,040
Speaker 1: what determines the light that comes from a star is

656
00:31:41,080 --> 00:31:43,320
Speaker 1: the velocity. And a bunch of listeners pointed this out

657
00:31:43,680 --> 00:31:45,640
Speaker 1: that things that are moving away from you will be

658
00:31:45,680 --> 00:31:48,320
Speaker 1: red shifted, just like a police siren moving away from

659
00:31:48,360 --> 00:31:50,640
Speaker 1: you will have a lower sound than a police siren

660
00:31:50,680 --> 00:31:52,960
Speaker 1: moving towards you. It's just a Doppler effect. And so

661
00:31:53,000 --> 00:31:54,880
Speaker 1: as star emitting light as it moves away from you

662
00:31:55,160 --> 00:31:57,440
Speaker 1: is going to get red shifted, and we use this

663
00:31:57,520 --> 00:32:00,000
Speaker 1: red shift to measure that velocity. It's like a huge

664
00:32:00,200 --> 00:32:03,600
Speaker 1: the important thing in astronomy. A star moving towards you

665
00:32:03,640 --> 00:32:05,880
Speaker 1: would be blue shifted, and we can tell the red

666
00:32:05,880 --> 00:32:08,720
Speaker 1: shift in the blue shift because we know the typical fingerprints.

667
00:32:09,080 --> 00:32:11,000
Speaker 1: Like you get a star you've never seen before and

668
00:32:11,040 --> 00:32:13,080
Speaker 1: you want to measure its red shift. Well, you might think, well,

669
00:32:13,080 --> 00:32:15,440
Speaker 1: how it I know it's impossible. If the star has

670
00:32:15,640 --> 00:32:19,360
Speaker 1: hydrogen lines but they're shifted by a few nanometers, and

671
00:32:19,440 --> 00:32:21,560
Speaker 1: it has magnesium lines and those are shifted by the

672
00:32:21,560 --> 00:32:25,600
Speaker 1: same number of nanometers, then the most likely scenario is, oh,

673
00:32:25,600 --> 00:32:28,160
Speaker 1: this isn't made of some new super weird metal that

674
00:32:28,240 --> 00:32:31,360
Speaker 1: looks like magnesium and hydrogen but shifted. It's just magnesium

675
00:32:31,440 --> 00:32:34,160
Speaker 1: and hydrogen and it's been shifted due to the red shift.

676
00:32:34,200 --> 00:32:37,360
Speaker 1: So you can fit these lines, these specter, these absorption

677
00:32:37,440 --> 00:32:40,840
Speaker 1: and emission lines, to tell you the frequency shift of

678
00:32:40,840 --> 00:32:44,280
Speaker 1: an individual star. And so that definitely affects the color

679
00:32:44,280 --> 00:32:46,720
Speaker 1: of the star in the sky. And almost everything in

680
00:32:46,760 --> 00:32:49,160
Speaker 1: the sky is moving away from us, so they're all

681
00:32:49,200 --> 00:32:49,840
Speaker 1: red shifted.

682
00:32:50,040 --> 00:32:52,640
Speaker 2: I'm having one of those moments where I'm just so

683
00:32:52,800 --> 00:32:55,680
Speaker 2: proud of our species for figuring all of this out,

684
00:32:55,720 --> 00:32:57,640
Speaker 2: Like that's so many different things to keep track of.

685
00:32:57,720 --> 00:32:59,880
Speaker 2: It's so incredible that we got there and that we

686
00:33:00,080 --> 00:33:03,080
Speaker 2: understand all of this stuff and anyway way to go humans.

687
00:33:03,520 --> 00:33:05,560
Speaker 1: This is the amazing thing about astronomy is that you

688
00:33:05,600 --> 00:33:08,440
Speaker 1: cannot leave the Earth. Mostly you've got to figure out

689
00:33:08,440 --> 00:33:11,840
Speaker 1: the puzzle of the universe from these clues. And we

690
00:33:11,880 --> 00:33:14,720
Speaker 1: didn't assemble this experiment in this way. We stumbled over

691
00:33:14,800 --> 00:33:17,280
Speaker 1: these things. People had moments of insight where they realized,

692
00:33:17,280 --> 00:33:20,520
Speaker 1: hold on a second, this pattern actually reveals this thing

693
00:33:20,600 --> 00:33:24,920
Speaker 1: about the universe. Those are incredible realizations, so powerful. And

694
00:33:25,000 --> 00:33:26,600
Speaker 1: let me just qualify what I said a moment ago

695
00:33:26,640 --> 00:33:30,360
Speaker 1: about everything moving away from us. Galaxies are moving away

696
00:33:30,360 --> 00:33:32,680
Speaker 1: from us, and those are all red shifted. Most of

697
00:33:32,720 --> 00:33:34,800
Speaker 1: the stars in the Milky Way are held together by

698
00:33:34,800 --> 00:33:37,680
Speaker 1: the gravity of the Milky Way, and so those aren't

699
00:33:37,760 --> 00:33:40,120
Speaker 1: red shifted and moving away from us. The stars in

700
00:33:40,160 --> 00:33:41,960
Speaker 1: the night sky are the ones from the Milky Way.

701
00:33:42,240 --> 00:33:44,280
Speaker 1: Those are the ones we can see. They're not red shifted.

702
00:33:44,400 --> 00:33:46,280
Speaker 1: But other galaxies are red shifted.

703
00:33:46,560 --> 00:33:49,160
Speaker 2: All right, Well, that is amazing. Let's take a break,

704
00:33:49,200 --> 00:33:50,960
Speaker 2: and when we get back, we're going to talk about

705
00:33:51,000 --> 00:34:10,120
Speaker 2: the color of our very own sun. All Right, we're back,

706
00:34:10,200 --> 00:34:12,200
Speaker 2: and Daniel wants to tell us about why Niel de

707
00:34:12,239 --> 00:34:13,320
Speaker 2: grass Tyson is wrong.

708
00:34:14,920 --> 00:34:17,319
Speaker 1: I don't want to say that. I do want to

709
00:34:17,360 --> 00:34:19,759
Speaker 1: dismantle a lot of pop sign myths that you.

710
00:34:19,800 --> 00:34:21,480
Speaker 2: Hear from Neil de grass Tyson.

711
00:34:22,360 --> 00:34:24,200
Speaker 1: I didn't say that. I didn't say that. I just

712
00:34:24,239 --> 00:34:26,319
Speaker 1: want to say that, you know, on this podcast, we'd

713
00:34:26,360 --> 00:34:29,040
Speaker 1: like to dig deep, well past the usual pop side

714
00:34:29,120 --> 00:34:32,600
Speaker 1: explanations and tell you what's really going on. So you know,

715
00:34:32,680 --> 00:34:34,520
Speaker 1: we're interested in the colors of the stars in general.

716
00:34:34,600 --> 00:34:36,640
Speaker 1: But of course our sun is near and dear to

717
00:34:36,680 --> 00:34:39,960
Speaker 1: our hearts. Why does the sun have its particular color?

718
00:34:40,160 --> 00:34:42,560
Speaker 1: And the Sun's color is actually fascinating because if you

719
00:34:42,560 --> 00:34:44,919
Speaker 1: were out in space and you were looking at the sun,

720
00:34:45,200 --> 00:34:47,040
Speaker 1: it's white, right, And what does it mean for the

721
00:34:47,080 --> 00:34:49,719
Speaker 1: sun to be white? White isn't like a color. It's

722
00:34:49,719 --> 00:34:51,799
Speaker 1: a mixture of the colors, and it's sort of the

723
00:34:51,800 --> 00:34:54,920
Speaker 1: way your brain responds when you see a very broad

724
00:34:55,040 --> 00:34:58,840
Speaker 1: spectrum of light across the visible range. So out of space,

725
00:34:58,880 --> 00:35:01,440
Speaker 1: the sun is white. Here on Earth because of the

726
00:35:01,440 --> 00:35:05,080
Speaker 1: effects of the atmosphere. The sun looks a little yellower, right,

727
00:35:05,160 --> 00:35:07,480
Speaker 1: because the atmosphere tends to scatter blue light, which is

728
00:35:07,480 --> 00:35:10,120
Speaker 1: why the sky, which doesn't have its color of its own,

729
00:35:10,480 --> 00:35:14,120
Speaker 1: looks blue, right, because it's reflecting blue light. Air itself

730
00:35:14,160 --> 00:35:16,399
Speaker 1: is not blue, but we see it as blue because

731
00:35:16,440 --> 00:35:19,480
Speaker 1: it's reflecting blue light. And so the sun has some

732
00:35:19,560 --> 00:35:21,640
Speaker 1: of the blue removed, which makes it look a little

733
00:35:21,719 --> 00:35:23,120
Speaker 1: yellower to our eyes.

734
00:35:23,480 --> 00:35:25,799
Speaker 2: Oh that's so cool. And again yet another thing that

735
00:35:25,800 --> 00:35:28,000
Speaker 2: we had to account for to understand all of this stuff.

736
00:35:28,040 --> 00:35:32,120
Speaker 1: Amazing, And the reason the sun glows at this color

737
00:35:32,320 --> 00:35:34,879
Speaker 1: is because of its temperature. The surface of the Sun

738
00:35:34,960 --> 00:35:38,000
Speaker 1: is about five thousand kelvin and what we're seeing when

739
00:35:38,080 --> 00:35:40,040
Speaker 1: we look at the Sun is its surface, right. We

740
00:35:40,080 --> 00:35:42,680
Speaker 1: can't see through it. It's opaque. Another bit of popsight

741
00:35:42,719 --> 00:35:44,840
Speaker 1: you hear a lot is that it takes like thousands

742
00:35:44,840 --> 00:35:47,200
Speaker 1: of years for a photon to go from the center

743
00:35:47,200 --> 00:35:49,359
Speaker 1: of the Sun to the surface. And like, I don't

744
00:35:49,360 --> 00:35:51,400
Speaker 1: even know what that means, because you know what's happening

745
00:35:51,480 --> 00:35:53,480
Speaker 1: is photons are made at the center of the sun,

746
00:35:53,520 --> 00:35:55,279
Speaker 1: but the sun is opaque, so then they just get

747
00:35:55,360 --> 00:35:58,600
Speaker 1: reabsorbed and they contribute to the overall heat of the sun.

748
00:35:59,000 --> 00:36:01,239
Speaker 1: An individual photon doesn't go from the center of the

749
00:36:01,280 --> 00:36:03,080
Speaker 1: sun to the edge of the sun. It just heats

750
00:36:03,160 --> 00:36:06,040
Speaker 1: up the sun and the surface emits a new fresh photon.

751
00:36:06,520 --> 00:36:09,400
Speaker 2: Oh interesting, I mean I can't say that. You know,

752
00:36:09,480 --> 00:36:11,680
Speaker 2: Ada came home from the playground. It was like, did

753
00:36:11,719 --> 00:36:13,719
Speaker 2: you know that a photon at the center of the

754
00:36:13,719 --> 00:36:15,719
Speaker 2: sun takes you know, blah blah blah get to the edge.

755
00:36:15,719 --> 00:36:18,240
Speaker 2: I had never heard that before, but now I'm enlightened.

756
00:36:18,320 --> 00:36:21,080
Speaker 1: I hear that a lot. Okay, And so you can

757
00:36:21,120 --> 00:36:23,600
Speaker 1: mimic the same spectrum that the sun makes by heating

758
00:36:23,680 --> 00:36:25,960
Speaker 1: up like a piece of tungsten to the same temperature.

759
00:36:26,000 --> 00:36:29,040
Speaker 1: You have a five thousand degree filament of tungsten, it

760
00:36:29,080 --> 00:36:31,920
Speaker 1: will emit in the same spectrum as the sun. Right,

761
00:36:32,000 --> 00:36:33,719
Speaker 1: it's not one hundred percent true, because the Sun is

762
00:36:33,760 --> 00:36:37,000
Speaker 1: not a perfect black body radiator, right, It does reflect

763
00:36:37,040 --> 00:36:39,359
Speaker 1: some things, it's not a perfect absorber. So the peak

764
00:36:39,400 --> 00:36:41,839
Speaker 1: of the distribution for the Sun is actually in the

765
00:36:41,840 --> 00:36:44,279
Speaker 1: green spectrum. And so this is why you might hear

766
00:36:44,400 --> 00:36:46,799
Speaker 1: some popseye folks being like, did you know the sun

767
00:36:46,960 --> 00:36:47,760
Speaker 1: is actually green?

768
00:36:48,280 --> 00:36:51,480
Speaker 2: Okay? Well, so now let's take down that hypothetical. Did

769
00:36:51,520 --> 00:36:53,560
Speaker 2: you know the sun is actually green? Person?

770
00:36:54,960 --> 00:36:56,560
Speaker 1: So saying that that the sun peaks in the green

771
00:36:56,680 --> 00:36:59,120
Speaker 1: is actually saying, if you had a perfect black body

772
00:36:59,200 --> 00:37:02,359
Speaker 1: radiator at five thousand kelvin, it would peak in the green.

773
00:37:02,680 --> 00:37:05,440
Speaker 1: But we don't have a perfect black body radiator. Our

774
00:37:05,480 --> 00:37:08,560
Speaker 1: son actually peaks in the violet. And where it peaks

775
00:37:08,560 --> 00:37:11,120
Speaker 1: depends a little bit on how you're doing the accounting,

776
00:37:11,280 --> 00:37:13,239
Speaker 1: like are you doing it in wavelength? Are you doing

777
00:37:13,280 --> 00:37:16,799
Speaker 1: in frequency? These things have a non linear relationship, and

778
00:37:16,840 --> 00:37:18,880
Speaker 1: so there's some like calculus that goes on there, but

779
00:37:19,160 --> 00:37:22,440
Speaker 1: which gets accounted into which bin And so it's not

780
00:37:22,480 --> 00:37:24,920
Speaker 1: really even true saying that the sun peaks in the green,

781
00:37:25,160 --> 00:37:26,959
Speaker 1: and even if it peaks in the green, you would

782
00:37:26,960 --> 00:37:29,319
Speaker 1: still see it as white in space. It's not like

783
00:37:29,400 --> 00:37:31,840
Speaker 1: out in space the sun is green or violet or

784
00:37:31,880 --> 00:37:34,799
Speaker 1: any of these things. Really, it's just most accurately said

785
00:37:34,840 --> 00:37:37,319
Speaker 1: that there's a broad spectrum that if the sun were

786
00:37:37,360 --> 00:37:39,560
Speaker 1: a perfect black body radiator, would peak in the green,

787
00:37:39,840 --> 00:37:41,160
Speaker 1: but it isn't, so it peaks in.

788
00:37:41,120 --> 00:37:44,560
Speaker 2: The violet, which is my favorite color. So thank you, universe.

789
00:37:44,880 --> 00:37:45,520
Speaker 2: There we go.

790
00:37:45,760 --> 00:37:47,279
Speaker 1: Why don't I see it on your arm. Then why

791
00:37:47,280 --> 00:37:49,000
Speaker 1: aren't you painting your launcher room violet.

792
00:37:49,160 --> 00:37:50,960
Speaker 2: If we had been doing this podcast when I was

793
00:37:51,000 --> 00:37:54,279
Speaker 2: painting my bathroom, you would have seen my purple arm.

794
00:37:56,560 --> 00:37:58,640
Speaker 1: Well, I have purple on the wall behind me as well.

795
00:37:58,680 --> 00:37:59,640
Speaker 1: See I'm a big fan.

796
00:38:00,040 --> 00:38:02,279
Speaker 2: Oh it's a great color, best color, all right, So

797
00:38:02,280 --> 00:38:04,480
Speaker 2: tell me about how we get colors for some other stars.

798
00:38:04,719 --> 00:38:08,120
Speaker 1: Yeah, So we've learned that star color depends on its

799
00:38:08,160 --> 00:38:11,120
Speaker 1: temperature and on what its atmosphere is made out of

800
00:38:11,239 --> 00:38:14,080
Speaker 1: and its velocity. So most of the stars in the

801
00:38:14,160 --> 00:38:17,040
Speaker 1: universe are smaller than our star. The Sun is a

802
00:38:17,080 --> 00:38:19,839
Speaker 1: big star compared to the average star, which is more

803
00:38:19,920 --> 00:38:24,520
Speaker 1: like a red dwarf. So smaller stars have less gravitational pressure,

804
00:38:24,719 --> 00:38:27,399
Speaker 1: so they're not as hot, so they burn and they

805
00:38:27,440 --> 00:38:30,120
Speaker 1: glow in the red more than in the yellow. So

806
00:38:30,120 --> 00:38:33,680
Speaker 1: that's why they're called red dwarfs. Right, So smaller stars

807
00:38:33,760 --> 00:38:37,439
Speaker 1: burn cooler and slower, they're longer lived, and they tend

808
00:38:37,440 --> 00:38:39,319
Speaker 1: to be redder. So a lot of the stars out

809
00:38:39,320 --> 00:38:41,520
Speaker 1: there in the universe are cooler on their surface than

810
00:38:41,560 --> 00:38:43,479
Speaker 1: are a star, but there are some that are hotter.

811
00:38:43,880 --> 00:38:47,560
Speaker 1: Blue giants, for example, super enormous stars very hot on

812
00:38:47,640 --> 00:38:50,719
Speaker 1: their surface because of the crazy fusion happening at their core,

813
00:38:50,960 --> 00:38:52,920
Speaker 1: they tend to glow in the blue. So if you

814
00:38:52,920 --> 00:38:55,000
Speaker 1: look at the spectra of stars, you see a really

815
00:38:55,040 --> 00:38:58,359
Speaker 1: big range. They are fewer that are bluer because those

816
00:38:58,400 --> 00:39:02,120
Speaker 1: are bigger and burn brighter and burn out faster. Red

817
00:39:02,160 --> 00:39:05,080
Speaker 1: stars tend to burn a lot longer, like our star

818
00:39:05,160 --> 00:39:08,000
Speaker 1: is going to last billions of years. Really big huge

819
00:39:08,040 --> 00:39:11,840
Speaker 1: blue stars can sometimes only last millions, where as little

820
00:39:11,920 --> 00:39:15,560
Speaker 1: tiny red giants we think maybe can last hundreds of

821
00:39:15,560 --> 00:39:18,560
Speaker 1: billions or even longer, much longer than the age of

822
00:39:18,600 --> 00:39:20,920
Speaker 1: the universe. So we don't really even have a measure

823
00:39:20,960 --> 00:39:21,480
Speaker 1: for it.

824
00:39:21,520 --> 00:39:25,919
Speaker 2: Is there any relationship between the temperature which is star

825
00:39:26,040 --> 00:39:29,480
Speaker 2: burns and what we think its ability to sustain life is?

826
00:39:30,000 --> 00:39:32,600
Speaker 1: Yeah, great question. We have this one clue, right that

827
00:39:32,680 --> 00:39:34,799
Speaker 1: we have life around a yellow star and not a

828
00:39:34,840 --> 00:39:37,880
Speaker 1: red star. And does that mean that life only happens

829
00:39:37,920 --> 00:39:40,319
Speaker 1: around yellow stars or are we weird and unusual and

830
00:39:40,360 --> 00:39:41,960
Speaker 1: most of the aliens out there look up at a

831
00:39:42,040 --> 00:39:45,200
Speaker 1: red sun. Yeah, we don't know. Red stars tend to

832
00:39:45,239 --> 00:39:48,040
Speaker 1: be a little bit more variable sometimes, and so there's

833
00:39:48,160 --> 00:39:50,840
Speaker 1: arguments there, but it's all based on this an equals

834
00:39:50,880 --> 00:39:53,440
Speaker 1: one so until we meet the aliens, we won't know

835
00:39:53,560 --> 00:39:55,040
Speaker 1: the answer to those questions.

836
00:39:55,120 --> 00:39:56,560
Speaker 2: And I feel like if you could be at the

837
00:39:56,600 --> 00:39:58,399
Speaker 2: right spot next to a red star, that would give

838
00:39:58,400 --> 00:40:00,360
Speaker 2: you more time for life to pop up. But I

839
00:40:00,400 --> 00:40:02,880
Speaker 2: guess if it's more variable, not necessarily and it's colder,

840
00:40:02,920 --> 00:40:04,759
Speaker 2: and what does that do? And anyway, all right, yeah,

841
00:40:04,800 --> 00:40:05,479
Speaker 2: we need more data.

842
00:40:05,560 --> 00:40:08,040
Speaker 1: We definitely need more data. And what's in the star

843
00:40:08,120 --> 00:40:11,120
Speaker 1: definitely does have an impact, Like if there's magnesium in

844
00:40:11,160 --> 00:40:14,359
Speaker 1: the atmosphere, then those lines are removed from the star.

845
00:40:14,440 --> 00:40:17,200
Speaker 1: But that doesn't really change the star that you see

846
00:40:17,239 --> 00:40:19,320
Speaker 1: from the naked eye because you can't tell that individual

847
00:40:19,400 --> 00:40:21,759
Speaker 1: slice of the spectrum has been removed. It still looks

848
00:40:21,800 --> 00:40:24,719
Speaker 1: red to your eye. But if you pass these things

849
00:40:24,760 --> 00:40:27,520
Speaker 1: through a prism, you will notice that different stars, even

850
00:40:27,520 --> 00:40:30,319
Speaker 1: if they have the same temperature, have different spectrum because

851
00:40:30,320 --> 00:40:32,600
Speaker 1: they have different lines removed, and that tells you what

852
00:40:32,760 --> 00:40:36,360
Speaker 1: they're made out of. Most stars still totally hydrogen, like

853
00:40:36,400 --> 00:40:40,360
Speaker 1: the universe started out all hydrogen. Mostly still hydrogen, but

854
00:40:40,480 --> 00:40:43,680
Speaker 1: the elemental mixture does affect the lines in the atmosphere,

855
00:40:43,680 --> 00:40:46,080
Speaker 1: so it will affect the color of the star technically.

856
00:40:46,400 --> 00:40:48,400
Speaker 2: So we've talked about a lot of different things that

857
00:40:48,480 --> 00:40:51,280
Speaker 2: influence star color. When I look at at the stars

858
00:40:51,280 --> 00:40:53,920
Speaker 2: at night, Am I understanding correctly that the thing that

859
00:40:54,040 --> 00:40:57,480
Speaker 2: mostly determines the color I see is how hot they're burning?

860
00:40:57,719 --> 00:41:00,000
Speaker 1: Yeah, which is mostly determined by how big they are?

861
00:41:00,520 --> 00:41:00,800
Speaker 2: Okay?

862
00:41:01,000 --> 00:41:05,120
Speaker 1: So yeah, Redder stars are smaller and bluer stars are bigger.

863
00:41:05,320 --> 00:41:07,439
Speaker 2: Got it. I'll appreciate that so much more now.

864
00:41:08,440 --> 00:41:10,880
Speaker 1: And it's incredible what we can learn about these stars

865
00:41:11,360 --> 00:41:13,319
Speaker 1: just from the pattern of the light, or that we

866
00:41:13,360 --> 00:41:15,600
Speaker 1: even figured out that you can break up light into components,

867
00:41:15,640 --> 00:41:18,320
Speaker 1: and that it contains all of this useful information right

868
00:41:18,560 --> 00:41:21,520
Speaker 1: always makes me wonder what happened we yet figured out

869
00:41:21,719 --> 00:41:26,200
Speaker 1: what information is landing on the planet screaming itself, screaming

870
00:41:26,239 --> 00:41:28,759
Speaker 1: clues about the universe that we haven't yet figured out

871
00:41:28,960 --> 00:41:30,640
Speaker 1: that in a few hundred years people will be like,

872
00:41:30,680 --> 00:41:32,719
Speaker 1: oh my gosh, you guys were such idiots.

873
00:41:33,640 --> 00:41:36,160
Speaker 2: You know, I wonder the same thing in biology, What

874
00:41:36,239 --> 00:41:38,000
Speaker 2: are the things that we're missing that people will laugh

875
00:41:38,040 --> 00:41:39,839
Speaker 2: at us for in the future. But you know, all

876
00:41:39,840 --> 00:41:42,640
Speaker 2: you can do is take incremental steps forward and then

877
00:41:42,640 --> 00:41:44,799
Speaker 2: be willing to take those steps backwards when you learn

878
00:41:44,800 --> 00:41:45,319
Speaker 2: that you're wrong.

879
00:41:45,560 --> 00:41:47,439
Speaker 1: Yeah, and take things apart and try to learn about

880
00:41:47,440 --> 00:41:51,279
Speaker 1: them right exactly. Pass your parasites through a prism, See

881
00:41:51,320 --> 00:41:52,360
Speaker 1: what bits they're made out of.

882
00:41:52,480 --> 00:41:56,160
Speaker 2: Tell me what you find out, and everybody out.

883
00:41:55,960 --> 00:41:58,839
Speaker 1: There come up with your favorite color and your favorite parasite.

884
00:41:58,960 --> 00:42:00,800
Speaker 2: Ah, what's your favorite parasite? Daniel?

885
00:42:02,920 --> 00:42:04,200
Speaker 1: All the ones that are not in me?

886
00:42:04,600 --> 00:42:06,480
Speaker 2: Oh, that's a lot, that's a lot. You must really

887
00:42:06,520 --> 00:42:07,359
Speaker 2: like parasites.

888
00:42:08,000 --> 00:42:10,200
Speaker 1: I approve of their choice to not be inside me

889
00:42:10,280 --> 00:42:10,560
Speaker 1: right now.

890
00:42:10,640 --> 00:42:12,720
Speaker 2: Yes, well, you know, as we were telling a listener

891
00:42:12,760 --> 00:42:14,280
Speaker 2: the other day, they don't have a lot of choice.

892
00:42:14,360 --> 00:42:16,000
Speaker 2: But I'm glad that they're not in you.

893
00:42:17,480 --> 00:42:19,520
Speaker 1: And I hope that this has helped you appreciate the

894
00:42:19,560 --> 00:42:21,640
Speaker 1: beauty of the night sky. And next time you're out

895
00:42:21,640 --> 00:42:25,400
Speaker 1: camping or on a beach in Costa Rica protecting turtles

896
00:42:25,440 --> 00:42:28,960
Speaker 1: from raccoons, you'll appreciate that the night sky is colorful

897
00:42:29,000 --> 00:42:32,279
Speaker 1: and that those colors communicate information about the nature of

898
00:42:32,360 --> 00:42:35,760
Speaker 1: the universe, what's going on in the hearts of these big,

899
00:42:35,920 --> 00:42:37,480
Speaker 1: furious balls of fusion.

900
00:42:37,840 --> 00:42:48,000
Speaker 2: Enjoy the night sky. Friends. Daniel and Kelly's Extraordinary Universe

901
00:42:48,040 --> 00:42:51,040
Speaker 2: is produced by iHeartRadio. We would love to hear from

902
00:42:51,040 --> 00:42:52,320
Speaker 2: you we really would.

903
00:42:52,480 --> 00:42:55,239
Speaker 1: We want to know what questions you have about this

904
00:42:55,440 --> 00:42:57,120
Speaker 1: extraordinary universe.

905
00:42:57,239 --> 00:43:00,200
Speaker 2: We want to know your thoughts on recent shows, suggests

906
00:43:00,239 --> 00:43:03,200
Speaker 2: for future shows. If you contact us, we will get

907
00:43:03,239 --> 00:43:03,680
Speaker 2: back to you.

908
00:43:03,880 --> 00:43:07,399
Speaker 1: We really mean it. We answer every message. Email us

909
00:43:07,440 --> 00:43:10,560
Speaker 1: at Questions at Danielankelly.

910
00:43:09,719 --> 00:43:11,760
Speaker 2: Dot org, or you can find us on social media.

911
00:43:11,840 --> 00:43:15,640
Speaker 2: We have accounts on x, Instagram, Blue Sky and on

912
00:43:15,719 --> 00:43:17,680
Speaker 2: all of those platforms. You can find us at D

913
00:43:18,120 --> 00:43:18,640
Speaker 2: and K.

914
00:43:19,200 --> 00:43:21,279
Speaker 1: Universe will be shy right to us