Peering deep into the dusty heart of our Milky Way galaxy using infrared vision, NASA’s Hubble Space Telescope reveals a rich tapestry of more than half a million stars.
NASA, ESA, and Hubble Heritage Team (STScI/AURA, Acknowledgment: T. Do, A.Ghez (UCLA), V. Bajaj (STScI)
Those tiny pinpoints of light glittering in the night sky are actually incredibly distant, giant, churning balls of gas. They produce huge quantities of light and heat!
In this episode, Mars interviews the biggest star in his eyes: the sun! We also ask astronomer Moiya McTier to help us count all the stars in the universe. And we'll hear a couple of the stories that people here on earth tell about the stars.
Plus, a brand new mystery sound and a Moment of Um that answers the question: how do whales drink?
Audio Transcript
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NARRATOR: You're listening to Brains On, where we're serious about being curious.
NARRATOR: Brains On is supported in part by a grant from the National Science Foundation.
LAKEN: Sanden, have you seen Molly anywhere?
SANDEN TOTTEN: Wait, what? I thought she was with you. I thought you two were in the studio about to start taping.
LAKEN: Well, we were, but right as we were about to start taping, she just said, nope, and ran out of the studio.
SANDEN TOTTEN: That is so strange. Oh, wait. Do you see that giant pile of pillows over there?
LAKEN: Uh-huh.
SANDEN TOTTEN: And do you see that pair of pink sneakers sticking out?
LAKEN: Oh, yeah. There she is.
SANDEN TOTTEN: [CLEARS THROAT] Uh, Molly?
MOLLY BLOOM: Oh, hi, Sanden.
SANDEN TOTTEN: Molly, why are you under the pillow pile?
MOLLY BLOOM: Oh, you know, just my usual preshow ritual of lying under 25 pillows.
SANDEN TOTTEN: Yeah. Could you come out here, please?
MOLLY BLOOM: OK. [RUSTLING SOUNDS]
LAKEN: What happened?
MOLLY BLOOM: I'm going to tell you something I've never told anyone before. Outer space [ECHOES] scares me.
LAKEN: What? Why? It's so awesome.
MOLLY BLOOM: Yeah, like, at first, but then, when I start to think about stars, I think about how far away they are. They're like, really, really far away, and my brain can't even handle thinking about that distance.
And then I think about how big the sun is, and that makes me feel really tiny. And then I think about how space goes on forever and there's so much of it, and I just can't deal. And then I need to go under a pile of pillows. [RUSTLING SOUNDS]
SANDEN TOTTEN: And she's back under the pillows.
LAKEN: Molly, space is really cool. There's so much to explore, mysteries to understand. Stars and planets and galaxies, we're a part of that awesomeness, too. Have you ever wished upon a star or looked at a full moon or watched a meteor shower? It's amazing.
[RUSTLING SOUNDS]
MOLLY BLOOM: Yeah, you're right. It is cool. So what if I'm small? I was always the shortest in my class anyway. I'm used to it.
LAKEN: That's the spirit.
SANDEN TOTTEN: Have a good taping, you two.
MOLLY BLOOM: Thanks, Sanden. Let's go, Laken. I'm just going to take this one pillow with me.
[SPACEY MUSIC]
You're listening to Brains On from American Public Media. I'm Molly Bloom, and my cohost today is Laken from Miller, Missouri. Hi, Laken.
LAKEN: Hi Molly.
MOLLY BLOOM: So Laken, you wrote in to us with a question about stars. So I'm wondering, how often do you look up at the stars?
LAKEN: Well, mainly, each time we're swimming late at night, I look up at the stars and just stare at them.
MOLLY BLOOM: Where do you go swimming late at night?
LAKEN: Well, we have a pool in our yard. And when we swim, I usually float on my back. And when I do that, I look at the stars.
MOLLY BLOOM: That sounds very peaceful. So does that kind of feel like you're floating in space when you do that?
LAKEN: Well, now that you said it, yeah, kind of.
[SPACEY MUSIC]
MOLLY BLOOM: Today, we're talking stars, and that's because you and lots of our listeners have written in with questions about them. We're going to start with this one from Isabella, Abigail, Savannah, and Mia.
Their question is, what makes stars look close together? When we look up at the night sky, the stars do look very close together, but they're not. They are very, very far away from us and very, very far away from each other.
Stars are giant balls of gas that produce huge amounts of light and heat. So even though they are very far away, we can still see the light they make from very, very, very, very far away. But you know, I should probably say, I don't know, 100 more "veries" because they are distances so far away that it's hard to imagine them.
LAKEN: Our sun is a star, and it's the closest one to Earth. But it's still, on average, 93 million miles away.
MOLLY BLOOM: It's so far away that it takes about eight minutes for light from the sun to travel to us here on Earth.
LAKEN: That's because light actually does travel.
MOLLY BLOOM: When you turn on the light in your living room, it feels like it's just there. That's because light travels fast-- 186,000 miles a second. [ZOOMING SOUND EFFECT]
LAKEN: Really, really fast. But the sun is so far away that it still takes eight minutes for its speedy light to reach us.
MOLLY BLOOM: So how far away is the next closest star to planet Earth? That star is called Proxima Centauri, and it's 5.8 trillion miles away.
LAKEN: That means it takes over four years for light from that star to reach us.
MOLLY BLOOM: And prepare your brains for this. Hold on, let me grab my pillow. OK. The farthest star ever seen by scientists is-- I can't say it.
LAKEN: That star is so far away, it takes 9 billion years for its light to reach us.
MOLLY BLOOM: Oh, wow. [CAR ENGINE REVVING] The universe is very large, and the stars that we admire at night are very far away.
LAKEN: So even though the stars are far away from each other, they look close together from where we sit. And that's because they're all so far away.
MOLLY BLOOM: Kind of like when you're in an airplane, and you see the tiny cities below you. They look pretty close together from up where you are, but if you were on the ground, you would have to drive to get there.
LAKEN: It's actually very cool when you think about it. These giant balls of burning gas look like beautiful pinpoints of light to us.
MOLLY BLOOM: Yes. And the light that we see has traveled for many, many years to make our beautiful, starry sky here on Earth.
[ROBOTIC NOISES]
ROBOT VOICE: Brains, brains, brains.
LAKEN: Our sun is such a big star.
MOLLY BLOOM: It's more of a medium-sized star, actually.
LAKEN: Oh. I meant such a celebrity-- it's famous all over the Earth. Like, everyone knows it. Plus, we all talk about it constantly. We tell time by it and draw pictures of it. And personally, I'm a big fan of its work.
MOLLY BLOOM: You mean light?
LAKEN: Yeah, I love light. And did you catch that interview planet Mars did with the sun last week?
MOLLY BLOOM: The sun gives interviews.
LAKEN: Rarely. That's why it was such a big deal. Here, you can watch it on Mars' YouTube channel. [WHOOSHING SOUND]
MARS: OK, I'm ready. No, I'm not freaking out. [PANTS NERVOUSLY] OK, OK. Get it together, Mars. You can do this interview. You're a professional. OK, I'm centering myself and-- wait. Oh, is this thing on? Oh, dang. OK.
Hey, everybody. It's me, your boy Mars here. Today, we have the biggest guest ever on the show. Like, literally, it's the biggest thing in our entire solar system. I've spent my entire life looking up to it, and you most definitely know it from his famous projects like being the center of our solar system and giving off light. It's the one, the only, the sun!
Let me just-- let me just-- hold on, I've got to connect-- [ZOOM JINGLE] OK, wait. OK, there we go. Are we connected? Can you hear me?
SUN: Hi, Mars. It's me, the sun. [HEAVENLY CHORUS]
MARS: Oh, wow. I am so honored to have you on my show. Thank you for taking time from your busy schedule to be here.
SUN: It's my pleasure.
MARS: You are, like, so famous-- bigger than the Beatles.
SUN: Oh, didn't they write a song about me? "Here Comes--" "Here Comes the Sun," something like that?
MARS: Like, I totally grew up watching you, and now I'm talking to you. I mean, wow.
SUN: So Mars, what do you want to know?
MARS: Right, right. Oh, OK. Well, I asked the fans to help me with some questions, so here's one from Jane.
JANE: My name is Jane, and I'm from Fair Oaks, California. My question is, what are stars made of?
SUN: That's a great question. On one level, we're made of our hopes. We're made of our dreams. We're made of our lived experiences. On another level, we're mostly hydrogen gas and some helium.
MARS: You're made of gas? Whoa. But you look so big and fiery.
SUN: Well, yeah, that's what happens when you have a whole lot of hydrogen in one place. You see, I'm so big, I create a lot of gravity. And that gravity pulls all my hydrogen into my center, smooshing it so tightly that it actually fuses together and forms helium. [BALLOON SOUND EFFECT] Mars, grab a piece of scrap paper.
MARS: OK, got one here.
SUN: Imagine that paper is the hydrogen. Now, try crumpling it up as small as you can.
MARS: OK, I'm doing it. I'm crumpling.
SUN: Now, imagine you could squish it and smash it and pack it so tightly, the molecules in it actually meld together and make something new. That's what happens when I super-smoosh the hydrogen. It makes helium. [BALLOON SOUND EFFECT]
MARS: Wow, that's impressive.
SUN: Yeah. When that change happens inside me, it releases a bunch of energy. That energy makes me hot-- like, 27 million degrees Fahrenheit at my core hot. Then that energy travels through me. Eventually, it's released as heat, light, and charged particles. That's what gives me my signature shine. [TWINKLING SOUND]
MARS: So rad. OK, here's another fan Q. This one's from Jonah.
JONAH: My name is Jonah from Ventura, California. My question is, how do stars form?
SUN: Yeah, I get this a lot. You know, I didn't start out this big and impressive. Like all of you, I had humble beginnings, which is true of all stars.
MARS: Wait, really?
SUN: Of course. There's no such thing as an overnight success. It takes a long time and a lot of work to get this fabulous. So let me set the scene. [MYSTICAL MUSIC] For me, it started over 4.5 billion years ago, when our whole solar system was just a cloud of gas and dust floating in space.
The real hero here is gravity. Gravity helped pull pieces of this dust and gas cloud together and eventually caused it all to collapse in on itself. Then, this material started spinning and spinning and formed a flat disk, like a giant pancake.
MARS: Whoa, like a cosmic pancake.
SUN: Totally. So in the center of that mega cosmic pancake, a bunch of material clumped together and formed a protostar. And thus, I was born. [BABY CRYING] But I was just a baby.
It took millions and millions of years of hard work and me compressing more and more to eventually get so dense that the hydrogen started fusing together to make helium. I grew in size and started radiating energy, and that's the story of my glow-up. [TRIUMPHANT TRUMPETS]
MARS: Wow. And like, me and Earth and the other planets, we were made out of the dust you left behind, right? Like, all that stuff in the cosmic pancake that was leftover after you formed?
SUN: Exactly.
MARS: So cool. OK, hey, how big exactly are you, Sun? I mean, if you don't mind my asking.
SUN: Oh, I love talking size, honey. I'm bigger than anything else in this solar system by a lot. You could fit 1 million Earths in me. If you wrapped a belt around my center, it would have to be roughly 2.7 million miles long. I am big, I am bold, I am beautiful.
MARS: Wow, that's amazing. OK, Sun, one last question. Can I have your autograph?
SUN: Of course. I'll have my people send you a signed headshot. What's your address, honey?
MARS: Space. Fourth rock from you, actually.
SUN: Perfect. I'll send it right out.
MARS: Well, thanks for joining us, Sun. And everyone else, don't forget to like and subscribe and leave your comments below. Mars out.
[ROCK MUSIC]
CREW: (SINGING) Ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, Brains On.
MOLLY BLOOM: Now it's time for your moment in the sound-guessing spotlight, Laken.
CREW: Shhhh. (WHISPERING) Mystery sound.
MOLLY BLOOM: Are you feeling ready?
LAKEN: Yeah.
MOLLY BLOOM: All right. Here it is.
[CREAKING SOUND]
Laken, what is your guess?
LAKEN: Well, if it has to do with stars, I don't know. But it sounds like a rubber band to me.
MOLLY BLOOM: So this does not necessarily have to do with stars.
LAKEN: OK.
MOLLY BLOOM: So does that change your guess at all?
LAKEN: I don't think so.
MOLLY BLOOM: So you're thinking rubber bands right now.
LAKEN: Yeah.
MOLLY BLOOM: OK. We'll give you another chance to guess and hear it a little bit later in the show.
[ENERGETIC DRUM MUSIC]
We're working on an episode all about the science of siblings, and we want to hear from you.
LAKEN: Do you have brothers or sisters? Are you an only child?
MOLLY BLOOM: Whatever your sibling situation is, we want to hear why you think it's the best. Tell us if you are the oldest, middle, youngest, or an only child, and what you think is great about it. Laken, what's great about your sibling situation?
LAKEN: Well, I'm the youngest.
MOLLY BLOOM: And how many siblings are there?
LAKEN: Altogether, there's four, and then I have three older sisters.
MOLLY BLOOM: OK. So is there anything that you love about being the youngest of four sisters?
LAKEN: They give me lots of folks when I'm sad.
MOLLY BLOOM: Aw, that's nice.
LAKEN: And I give them hugs back.
MOLLY BLOOM: Send your answers to us at brainson.org/contact. Oh, and we've got big news. Brains On is coming out in book format. The new book is called It's Alive-- From Neurons and Narwhals to the Fungus Among Us. It's full of comics, mystery photos, super matchups, and a ton of freaky and fascinating facts about living creatures. You could order a copy now by going to brainson.org.
LAKEN: You can also go there and send us mystery sounds, drawings of Mars interviewing the sun, or a question.
MOLLY BLOOM: Like this one.
ELI: Hi, my name is Eli from Raleigh, North Carolina. And my question is, do whales drink? And if so, how?
MOLLY BLOOM: We'll answer that at the end of the episode. And we'll also give a super shout out to the latest group to be added to the Brains Honor Roll.
LAKEN: So keep listening.
MOLLY BLOOM: You are listening to Brains On from American Public Media. I'm Molly.
LAKEN: And I'm Laken.
MOLLY BLOOM: Are you ready to hear the mystery sound again, Laken?
LAKEN: Yes.
MOLLY BLOOM: Awesome. Here it is.
[CREAKING SOUND]
LAKEN: I feel like I have a memory of hearing this not during what we were doing last--
MOLLY BLOOM: So you feel like you've heard this in your life somewhere?
LAKEN: Yeah. I feel like it was at a park, but I don't know why.
MOLLY BLOOM: So something about the park.
LAKEN: Maybe, like, a swing or something.
MOLLY BLOOM: Ooh, I like that. That was really good thinking. Yeah, mystery sounds are tough. When you hear them out of context, it's like, I don't know. All right. You ready to hear the answer?
LAKEN: Yeah.
MOLLY BLOOM: All right. Here it is.
COLIN: My name is Colin, and I am from Toronto, Ontario, Canada. That was the sound of a pine borer beetle. I recorded the sound of a cottage in Georgian Bay. Pine borers are beetles that eat the inside of sick pine trees and make this sound when they do. The sound reminds me of a rocking chair because they both make a similar creaking sound.
[CREAKING SOUND]
MOLLY BLOOM: So it was a beetle, a borer in a tree.
LAKEN: That's kind of weird because I heard the rocking chair noise. We have two rocking chairs in our house. So that's probably where I heard it from. And then I just thought, oh, maybe swings, something you can sit on.
MOLLY BLOOM: Yeah, when I heard it, I definitely thought it was, like, headphones squeaking or a rocking chair, too.
LAKEN: Yeah.
MOLLY BLOOM: It's kind of cool that a little, tiny borer can make that noise.
CREW: (SUNG OPERATICALLY) Brains on.
MOLLY BLOOM: We asked Brains On listeners to think about what they would name a star if they ever got the chance.
LAKEN: The names you came up with would definitely light up the night sky.
ALENIA: My star name is Spiral Dome. I picked "spiral" because a star is a swirling mix of dust and gas and "dome" because, when I look at the night sky, it looks like a dome.
ELLIA: If I could name a star, I would name it Tano. Tano is the last name of my favorite character in Star Wars.
PHILLIP: If I had the chance to name a star, it would be named Chicken Nugget.
NUMI: If I had a star, I would name it by the sunset because some people name their honeys and their babies by the sunset.
HADIJA: If they told me to name a star, I would name it Sleepy Dream.
ANSHU: If I were to name a star, I would name it Lamperó Astéri, which is Greek for "bright star."
LOLA: If I could name a star, I'd name it Rubus Idaeus because that's the scientific name for raspberry, and the middle of the Milky Way actually smells like raspberry due to a chemical.
MOLLY BLOOM: Raspberries? It's true. Astronomers have identified the chemical ethyl formate in the Milky Way. It's the same chemical that makes raspberries taste like raspberries.
Thanks to Lola for that fact and name. Thanks also to Alenia, Ellia, Phillip, Numi, Hadija, and Anshu for sending in those star names. We'll hear even more star names in just a bit.
[SPACEY MUSIC]
You know, Laken, hearing all those names and looking up in the sky reminds me that there are a lot of stars out there and-- wait a minute. I need to grab my pillow again before we get to this next question.
ANNALIA: My name is Annalia, and I'm from Northampton, Mass. My question is, how many stars are there in the universe?
MOLLY BLOOM: Phew. Oh boy. Well, this calls for more than a pillow. Maybe I should ask our friend, Moiya McTier. She studies stars at Columbia University.
MOIYA MCTIER: Oh, in the whole universe? That's tricky. So we have an idea of how many stars there are in the Milky Way galaxy. And we did that by looking at how bright different parts of the galaxy-- and we know how bright different types of stars are, so we can do some kind of math to figure out how many stars we have. And we also have an idea of how many galaxies there are in the observable universe.
And so we can just multiply the number of stars in the Milky Way by the number of galaxies that we can see. And when we do that, we get that there are about 100 billion stars in the Milky Way and 100 billion galaxies like it. Which mean there should be-- I think the number is 10 sextillion.
MOLLY BLOOM: 10 sextillion-- that's way bigger than a million, bigger than a billion, bigger than a trillion. It's the number 10 followed by 20 zeroes. So many stars.
All the stars we can see are part of the Milky Way galaxy. Moiya says a galaxy is a collection of stars, gas, dust, and dark matter that are all bound together by gravity. The Milky Way is part of a larger group of about 50 to 100 galaxies, also bound together by gravity.
MOIYA MCTIER: There are parts of the universe that we can't see, and so there are-- we don't even know how many galaxies there are in the universe, the part of the universe that we can't see. So no one can actually answer the question of how many stars there are in the whole universe.
MOLLY BLOOM: Stars come in different sizes, too. Our shining star, the sun, is a pretty average-sized star. And by average, I mean it can fit about 1 million Earths in it.
MOIYA MCTIER: There are stars that are up to, like, 50 to 100 times bigger than our sun. Those are really big ones. We call them O-type stars. They burn really hot, and they live really short lives.
But then there are also stars that can be almost 7% the size of the sun, so, like, 1/10 the size of the sun. And those are called M-dwarf stars. They're really small. They are pretty cool by comparison, only about 3,000 degrees Kelvin. And they live for a really long time. They live for trillions of years.
MOLLY BLOOM: The numbers we're talking about are so huge-- trillions of years, sextillion stars. I asked Moiya how she can think about it without hiding under a pile of pillows.
MOIYA MCTIER: In some ways, it brings me comfort, actually, to think about how huge the universe is and how tiny our entire planet is compared to the universe. [MYSTICAL MUSIC] When astronauts come back from space, they talk about something called the "pale blue dot phenomenon." And it's when you can look at the entire Earth from outside of it.
It gives you a whole new perspective on life and humanity, and it makes you really appreciate what it means to be a human living on this tiny rock, hurtling through space at thousands of kilometers per second. Which is pretty cool, I think. And it's not something you can get if you don't remove yourself from the small confines of Earth and start thinking about the large scales that space has.
MOLLY BLOOM: Before we move on, let's take a listen to a few more of your space-rific star names.
FIONA: If I discovered a new star I would name it Betelgeuse 2 because I already know there is a star named Betelgeuse, and I watched the movie Beetlejuice a million times.
ATHOS: Hi, Brains On. I would call a star God because it is in the sky.
PRIYA: What I would name a star is Magnus.
ETHAN: My star name would be Intergalactic Push-Up.
DUHA: I will call my star Star Fruit because I like to eat star fruit, and it has the word "star" in it.
JULIA: I would name my star Rosabell because Rosie and Bella are my cats names that I love so much. And Rosie and Bella combined equals Rosabell.
ZARA: If I had to name a star, I would name it Calidum Album because it's Latin for "white hot," and stars are very hot.
MOLLY BLOOM: Thanks to Fiona, Athos, Priya, Ethan, Duha, Julia and Zara for sending in those names.
[REVERSED AUDIO SOUND]
CROWD: Brains on!
MOLLY BLOOM: People around the world have been naming stars and sharing stories about them for a long time. We can see a lot of the same stars, so there are lots of different names and stories for the same parts of the night sky.
One thing lots of people have looked up at is actually a bunch of stars at once. It's light from the core of our galaxy, the Milky Way. It shows up as a hazy band in the sky. Here are a couple of names for the Milky Way from around the world.
ANNETTE LEE: [LAKOTA], and this is "the world of the spirits."
JOSE DE PRADA-SAMPER: [NON-ENGLISH], "the white ashes."
MOLLY BLOOM: That's Jose de Prada-Samper and Annette Lee. They both told us different folk tales about where the Milky Way came from. Annette's a Native American astrophysicist and artist, and her story comes from the Lakota tribe, where the Milky Way is known as the road of the spirits.
[ADVENTUROUS MUSIC]
ANNETTE LEE: So in our Indigenous way of knowing, we came here from another place, and we call this place the spirit world or the star world. Our spirits have lived really long time, and we'll keep going after this. So there's a "before this" time and a "after this" time. And so before we were here, we were in the star world.
But to get from the star world to here, there was a journey, a whole process. So the Milky Way plays an important role because it's a really big, important path. So think of-- like, you're in this forest. Instead of trees, you've got all of these stars. You have to try to find your way without getting lost.
So a path through the forest, through the stars is going to be really, really helpful. And so there's this path that we have in the sky, and that's the Milky Way. It's the road of the spirits or the path of the spirits.
MOLLY BLOOM: Jose de Prada-Samper told us another story about the Milky Way. This one is from the Southern hemisphere. He's studied a tribe of people who lived in Southern Africa.
JOSE DE PRADA-SAMPER: The !Kung people lived, and their descendents now live, in the Northern Cape province of South Africa. And in the traditional !Kung language, the name of the Milky Way is [NON-ENGLISH], "the white ashes." The name, translated, means "white ashes."
And it is a very well-known story that it was a girl who created the Milky Way. In the !Kung story, the girl is in a separate hut from that she usually lives so that her elders can teach her because she's entering a completely new period in her life. She cannot be with her family. She cannot play with her friends. And that's why she's very frustrated and very angry.
She had a nice fire, but the fire, now, is off. And she sees the beautiful ashes, white ashes there on the surface. And she picks-- with both hands, she picks the ashes. And then she throws them into the sky and says, these ashes will become the Milky Way. And she tells the ashes, you must stay in the sky so that the people see you, so that you give light to the people when they are returning home.
And because she is so powerful now, because she's undergoing this change, what she says becomes true. The ashes turn into stars, and the Milky Way begins to sail in the sky.
MOLLY BLOOM: The stars have helped people remember and share stories like these for a long time. People have also used the stars to find their way around and understand the weather and the seasons. Looking up at the vast, star-filled night sky has been important to humans for a very long time.
[JAUNTY ELECTRONIC MUSIC]
LAKEN: Stars are big balls of gas that are very far away from us.
MOLLY BLOOM: Even though they're huge, they look like tiny pinpoints of light because they're so far away.
LAKEN: The sun is the closest star to us and is the center of our solar system.
MOLLY BLOOM: Stars begin to form when clouds of dust and gas collapse.
LAKEN: Our sun is an average-sized star. Some are smaller, and some are much bigger.
MOLLY BLOOM: People have had names and stories about stars for thousands of years. That's it for this episode of Brains On.
LAKEN: It was produced by Marc Sanchez, Menaka Wilhelm, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: We had production help from Christina Lopez and Amy McCann, who went to great lengths to help us record today's episode. We had engineering help from Eric Romani. Special thanks to Phil Plate and Nora McInerney.
LAKEN: Brains On is a nonprofit public radio show.
MOLLY BLOOM: You can support us and help us keep making episodes at brainson.org/fans.
LAKEN: Now, before we go it's time for our Moment of Um.
[CHORUS OF PEOPLE SAYING "UM"]
ELI: Do whales drink? And if so, how?
JOY REIDENBERG: Hi. My name is Joy Reidenberg, and I am a professor at the Icahn School of Medicine at Mount Sinai. But my research is in comparative anatomy, looking at animals adapted to extreme environments-- in particular, whales and dolphins.
Whales can drink, but they usually don't drink. And the reason for that is that the water that they're swimming in is very salty. So if they drink saltwater, then they need to get rid of the extra salt. It's more efficient for them to simply get the water from the food that they eat because there is freshwater inside the prey that they consume.
But if they do swallow some seawater by accident as they're swallowing their food, they can get rid of that extra salt because they have very special kidneys. Their kidneys look like a bunch of grapes. Each little ball of that kidney is a separate, miniature kidney.
So it looks more like they have hundreds of little kidneys rather than one big kidney, the way we do. That provides a lot of surface area in the kidney for concentrating the urine so that the water is retained and only the salts are excreted with just the smallest amount of water.
So that kind of a kidney is called a reniculate kidney, and it's only found in marine mammals and bears, interestingly. But some bears are actually marine mammals, like polar bears. They swim in saltwater, and they can do so for many days at a time. So you find that in seals and in sea lions and all of the different dolphins and porpoises as well as the big whales.
MOLLY BLOOM: OK. Who's ready to drink in this list? I know I am. It's time for the Brains Honor Roll. This is the group of listeners who keep us going by sending us ideas, questions, mystery sounds, drawings, and high fives.
[LISTING HONOR ROLL]
Brains On will be back soon with more answers to your questions.
LAKEN: Thanks for listening.
NARRATOR: Brains On is supported in part by a grant from the National Science Foundation.
LAKEN: Sanden, have you seen Molly anywhere?
SANDEN TOTTEN: Wait, what? I thought she was with you. I thought you two were in the studio about to start taping.
LAKEN: Well, we were, but right as we were about to start taping, she just said, nope, and ran out of the studio.
SANDEN TOTTEN: That is so strange. Oh, wait. Do you see that giant pile of pillows over there?
LAKEN: Uh-huh.
SANDEN TOTTEN: And do you see that pair of pink sneakers sticking out?
LAKEN: Oh, yeah. There she is.
SANDEN TOTTEN: [CLEARS THROAT] Uh, Molly?
MOLLY BLOOM: Oh, hi, Sanden.
SANDEN TOTTEN: Molly, why are you under the pillow pile?
MOLLY BLOOM: Oh, you know, just my usual preshow ritual of lying under 25 pillows.
SANDEN TOTTEN: Yeah. Could you come out here, please?
MOLLY BLOOM: OK. [RUSTLING SOUNDS]
LAKEN: What happened?
MOLLY BLOOM: I'm going to tell you something I've never told anyone before. Outer space [ECHOES] scares me.
LAKEN: What? Why? It's so awesome.
MOLLY BLOOM: Yeah, like, at first, but then, when I start to think about stars, I think about how far away they are. They're like, really, really far away, and my brain can't even handle thinking about that distance.
And then I think about how big the sun is, and that makes me feel really tiny. And then I think about how space goes on forever and there's so much of it, and I just can't deal. And then I need to go under a pile of pillows. [RUSTLING SOUNDS]
SANDEN TOTTEN: And she's back under the pillows.
LAKEN: Molly, space is really cool. There's so much to explore, mysteries to understand. Stars and planets and galaxies, we're a part of that awesomeness, too. Have you ever wished upon a star or looked at a full moon or watched a meteor shower? It's amazing.
[RUSTLING SOUNDS]
MOLLY BLOOM: Yeah, you're right. It is cool. So what if I'm small? I was always the shortest in my class anyway. I'm used to it.
LAKEN: That's the spirit.
SANDEN TOTTEN: Have a good taping, you two.
MOLLY BLOOM: Thanks, Sanden. Let's go, Laken. I'm just going to take this one pillow with me.
[SPACEY MUSIC]
You're listening to Brains On from American Public Media. I'm Molly Bloom, and my cohost today is Laken from Miller, Missouri. Hi, Laken.
LAKEN: Hi Molly.
MOLLY BLOOM: So Laken, you wrote in to us with a question about stars. So I'm wondering, how often do you look up at the stars?
LAKEN: Well, mainly, each time we're swimming late at night, I look up at the stars and just stare at them.
MOLLY BLOOM: Where do you go swimming late at night?
LAKEN: Well, we have a pool in our yard. And when we swim, I usually float on my back. And when I do that, I look at the stars.
MOLLY BLOOM: That sounds very peaceful. So does that kind of feel like you're floating in space when you do that?
LAKEN: Well, now that you said it, yeah, kind of.
[SPACEY MUSIC]
MOLLY BLOOM: Today, we're talking stars, and that's because you and lots of our listeners have written in with questions about them. We're going to start with this one from Isabella, Abigail, Savannah, and Mia.
Their question is, what makes stars look close together? When we look up at the night sky, the stars do look very close together, but they're not. They are very, very far away from us and very, very far away from each other.
Stars are giant balls of gas that produce huge amounts of light and heat. So even though they are very far away, we can still see the light they make from very, very, very, very far away. But you know, I should probably say, I don't know, 100 more "veries" because they are distances so far away that it's hard to imagine them.
LAKEN: Our sun is a star, and it's the closest one to Earth. But it's still, on average, 93 million miles away.
MOLLY BLOOM: It's so far away that it takes about eight minutes for light from the sun to travel to us here on Earth.
LAKEN: That's because light actually does travel.
MOLLY BLOOM: When you turn on the light in your living room, it feels like it's just there. That's because light travels fast-- 186,000 miles a second. [ZOOMING SOUND EFFECT]
LAKEN: Really, really fast. But the sun is so far away that it still takes eight minutes for its speedy light to reach us.
MOLLY BLOOM: So how far away is the next closest star to planet Earth? That star is called Proxima Centauri, and it's 5.8 trillion miles away.
LAKEN: That means it takes over four years for light from that star to reach us.
MOLLY BLOOM: And prepare your brains for this. Hold on, let me grab my pillow. OK. The farthest star ever seen by scientists is-- I can't say it.
LAKEN: That star is so far away, it takes 9 billion years for its light to reach us.
MOLLY BLOOM: Oh, wow. [CAR ENGINE REVVING] The universe is very large, and the stars that we admire at night are very far away.
LAKEN: So even though the stars are far away from each other, they look close together from where we sit. And that's because they're all so far away.
MOLLY BLOOM: Kind of like when you're in an airplane, and you see the tiny cities below you. They look pretty close together from up where you are, but if you were on the ground, you would have to drive to get there.
LAKEN: It's actually very cool when you think about it. These giant balls of burning gas look like beautiful pinpoints of light to us.
MOLLY BLOOM: Yes. And the light that we see has traveled for many, many years to make our beautiful, starry sky here on Earth.
[ROBOTIC NOISES]
ROBOT VOICE: Brains, brains, brains.
LAKEN: Our sun is such a big star.
MOLLY BLOOM: It's more of a medium-sized star, actually.
LAKEN: Oh. I meant such a celebrity-- it's famous all over the Earth. Like, everyone knows it. Plus, we all talk about it constantly. We tell time by it and draw pictures of it. And personally, I'm a big fan of its work.
MOLLY BLOOM: You mean light?
LAKEN: Yeah, I love light. And did you catch that interview planet Mars did with the sun last week?
MOLLY BLOOM: The sun gives interviews.
LAKEN: Rarely. That's why it was such a big deal. Here, you can watch it on Mars' YouTube channel. [WHOOSHING SOUND]
MARS: OK, I'm ready. No, I'm not freaking out. [PANTS NERVOUSLY] OK, OK. Get it together, Mars. You can do this interview. You're a professional. OK, I'm centering myself and-- wait. Oh, is this thing on? Oh, dang. OK.
Hey, everybody. It's me, your boy Mars here. Today, we have the biggest guest ever on the show. Like, literally, it's the biggest thing in our entire solar system. I've spent my entire life looking up to it, and you most definitely know it from his famous projects like being the center of our solar system and giving off light. It's the one, the only, the sun!
Let me just-- let me just-- hold on, I've got to connect-- [ZOOM JINGLE] OK, wait. OK, there we go. Are we connected? Can you hear me?
SUN: Hi, Mars. It's me, the sun. [HEAVENLY CHORUS]
MARS: Oh, wow. I am so honored to have you on my show. Thank you for taking time from your busy schedule to be here.
SUN: It's my pleasure.
MARS: You are, like, so famous-- bigger than the Beatles.
SUN: Oh, didn't they write a song about me? "Here Comes--" "Here Comes the Sun," something like that?
MARS: Like, I totally grew up watching you, and now I'm talking to you. I mean, wow.
SUN: So Mars, what do you want to know?
MARS: Right, right. Oh, OK. Well, I asked the fans to help me with some questions, so here's one from Jane.
JANE: My name is Jane, and I'm from Fair Oaks, California. My question is, what are stars made of?
SUN: That's a great question. On one level, we're made of our hopes. We're made of our dreams. We're made of our lived experiences. On another level, we're mostly hydrogen gas and some helium.
MARS: You're made of gas? Whoa. But you look so big and fiery.
SUN: Well, yeah, that's what happens when you have a whole lot of hydrogen in one place. You see, I'm so big, I create a lot of gravity. And that gravity pulls all my hydrogen into my center, smooshing it so tightly that it actually fuses together and forms helium. [BALLOON SOUND EFFECT] Mars, grab a piece of scrap paper.
MARS: OK, got one here.
SUN: Imagine that paper is the hydrogen. Now, try crumpling it up as small as you can.
MARS: OK, I'm doing it. I'm crumpling.
SUN: Now, imagine you could squish it and smash it and pack it so tightly, the molecules in it actually meld together and make something new. That's what happens when I super-smoosh the hydrogen. It makes helium. [BALLOON SOUND EFFECT]
MARS: Wow, that's impressive.
SUN: Yeah. When that change happens inside me, it releases a bunch of energy. That energy makes me hot-- like, 27 million degrees Fahrenheit at my core hot. Then that energy travels through me. Eventually, it's released as heat, light, and charged particles. That's what gives me my signature shine. [TWINKLING SOUND]
MARS: So rad. OK, here's another fan Q. This one's from Jonah.
JONAH: My name is Jonah from Ventura, California. My question is, how do stars form?
SUN: Yeah, I get this a lot. You know, I didn't start out this big and impressive. Like all of you, I had humble beginnings, which is true of all stars.
MARS: Wait, really?
SUN: Of course. There's no such thing as an overnight success. It takes a long time and a lot of work to get this fabulous. So let me set the scene. [MYSTICAL MUSIC] For me, it started over 4.5 billion years ago, when our whole solar system was just a cloud of gas and dust floating in space.
The real hero here is gravity. Gravity helped pull pieces of this dust and gas cloud together and eventually caused it all to collapse in on itself. Then, this material started spinning and spinning and formed a flat disk, like a giant pancake.
MARS: Whoa, like a cosmic pancake.
SUN: Totally. So in the center of that mega cosmic pancake, a bunch of material clumped together and formed a protostar. And thus, I was born. [BABY CRYING] But I was just a baby.
It took millions and millions of years of hard work and me compressing more and more to eventually get so dense that the hydrogen started fusing together to make helium. I grew in size and started radiating energy, and that's the story of my glow-up. [TRIUMPHANT TRUMPETS]
MARS: Wow. And like, me and Earth and the other planets, we were made out of the dust you left behind, right? Like, all that stuff in the cosmic pancake that was leftover after you formed?
SUN: Exactly.
MARS: So cool. OK, hey, how big exactly are you, Sun? I mean, if you don't mind my asking.
SUN: Oh, I love talking size, honey. I'm bigger than anything else in this solar system by a lot. You could fit 1 million Earths in me. If you wrapped a belt around my center, it would have to be roughly 2.7 million miles long. I am big, I am bold, I am beautiful.
MARS: Wow, that's amazing. OK, Sun, one last question. Can I have your autograph?
SUN: Of course. I'll have my people send you a signed headshot. What's your address, honey?
MARS: Space. Fourth rock from you, actually.
SUN: Perfect. I'll send it right out.
MARS: Well, thanks for joining us, Sun. And everyone else, don't forget to like and subscribe and leave your comments below. Mars out.
[ROCK MUSIC]
CREW: (SINGING) Ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, Brains On.
MOLLY BLOOM: Now it's time for your moment in the sound-guessing spotlight, Laken.
CREW: Shhhh. (WHISPERING) Mystery sound.
MOLLY BLOOM: Are you feeling ready?
LAKEN: Yeah.
MOLLY BLOOM: All right. Here it is.
[CREAKING SOUND]
Laken, what is your guess?
LAKEN: Well, if it has to do with stars, I don't know. But it sounds like a rubber band to me.
MOLLY BLOOM: So this does not necessarily have to do with stars.
LAKEN: OK.
MOLLY BLOOM: So does that change your guess at all?
LAKEN: I don't think so.
MOLLY BLOOM: So you're thinking rubber bands right now.
LAKEN: Yeah.
MOLLY BLOOM: OK. We'll give you another chance to guess and hear it a little bit later in the show.
[ENERGETIC DRUM MUSIC]
We're working on an episode all about the science of siblings, and we want to hear from you.
LAKEN: Do you have brothers or sisters? Are you an only child?
MOLLY BLOOM: Whatever your sibling situation is, we want to hear why you think it's the best. Tell us if you are the oldest, middle, youngest, or an only child, and what you think is great about it. Laken, what's great about your sibling situation?
LAKEN: Well, I'm the youngest.
MOLLY BLOOM: And how many siblings are there?
LAKEN: Altogether, there's four, and then I have three older sisters.
MOLLY BLOOM: OK. So is there anything that you love about being the youngest of four sisters?
LAKEN: They give me lots of folks when I'm sad.
MOLLY BLOOM: Aw, that's nice.
LAKEN: And I give them hugs back.
MOLLY BLOOM: Send your answers to us at brainson.org/contact. Oh, and we've got big news. Brains On is coming out in book format. The new book is called It's Alive-- From Neurons and Narwhals to the Fungus Among Us. It's full of comics, mystery photos, super matchups, and a ton of freaky and fascinating facts about living creatures. You could order a copy now by going to brainson.org.
LAKEN: You can also go there and send us mystery sounds, drawings of Mars interviewing the sun, or a question.
MOLLY BLOOM: Like this one.
ELI: Hi, my name is Eli from Raleigh, North Carolina. And my question is, do whales drink? And if so, how?
MOLLY BLOOM: We'll answer that at the end of the episode. And we'll also give a super shout out to the latest group to be added to the Brains Honor Roll.
LAKEN: So keep listening.
MOLLY BLOOM: You are listening to Brains On from American Public Media. I'm Molly.
LAKEN: And I'm Laken.
MOLLY BLOOM: Are you ready to hear the mystery sound again, Laken?
LAKEN: Yes.
MOLLY BLOOM: Awesome. Here it is.
[CREAKING SOUND]
LAKEN: I feel like I have a memory of hearing this not during what we were doing last--
MOLLY BLOOM: So you feel like you've heard this in your life somewhere?
LAKEN: Yeah. I feel like it was at a park, but I don't know why.
MOLLY BLOOM: So something about the park.
LAKEN: Maybe, like, a swing or something.
MOLLY BLOOM: Ooh, I like that. That was really good thinking. Yeah, mystery sounds are tough. When you hear them out of context, it's like, I don't know. All right. You ready to hear the answer?
LAKEN: Yeah.
MOLLY BLOOM: All right. Here it is.
COLIN: My name is Colin, and I am from Toronto, Ontario, Canada. That was the sound of a pine borer beetle. I recorded the sound of a cottage in Georgian Bay. Pine borers are beetles that eat the inside of sick pine trees and make this sound when they do. The sound reminds me of a rocking chair because they both make a similar creaking sound.
[CREAKING SOUND]
MOLLY BLOOM: So it was a beetle, a borer in a tree.
LAKEN: That's kind of weird because I heard the rocking chair noise. We have two rocking chairs in our house. So that's probably where I heard it from. And then I just thought, oh, maybe swings, something you can sit on.
MOLLY BLOOM: Yeah, when I heard it, I definitely thought it was, like, headphones squeaking or a rocking chair, too.
LAKEN: Yeah.
MOLLY BLOOM: It's kind of cool that a little, tiny borer can make that noise.
CREW: (SUNG OPERATICALLY) Brains on.
MOLLY BLOOM: We asked Brains On listeners to think about what they would name a star if they ever got the chance.
LAKEN: The names you came up with would definitely light up the night sky.
ALENIA: My star name is Spiral Dome. I picked "spiral" because a star is a swirling mix of dust and gas and "dome" because, when I look at the night sky, it looks like a dome.
ELLIA: If I could name a star, I would name it Tano. Tano is the last name of my favorite character in Star Wars.
PHILLIP: If I had the chance to name a star, it would be named Chicken Nugget.
NUMI: If I had a star, I would name it by the sunset because some people name their honeys and their babies by the sunset.
HADIJA: If they told me to name a star, I would name it Sleepy Dream.
ANSHU: If I were to name a star, I would name it Lamperó Astéri, which is Greek for "bright star."
LOLA: If I could name a star, I'd name it Rubus Idaeus because that's the scientific name for raspberry, and the middle of the Milky Way actually smells like raspberry due to a chemical.
MOLLY BLOOM: Raspberries? It's true. Astronomers have identified the chemical ethyl formate in the Milky Way. It's the same chemical that makes raspberries taste like raspberries.
Thanks to Lola for that fact and name. Thanks also to Alenia, Ellia, Phillip, Numi, Hadija, and Anshu for sending in those star names. We'll hear even more star names in just a bit.
[SPACEY MUSIC]
You know, Laken, hearing all those names and looking up in the sky reminds me that there are a lot of stars out there and-- wait a minute. I need to grab my pillow again before we get to this next question.
ANNALIA: My name is Annalia, and I'm from Northampton, Mass. My question is, how many stars are there in the universe?
MOLLY BLOOM: Phew. Oh boy. Well, this calls for more than a pillow. Maybe I should ask our friend, Moiya McTier. She studies stars at Columbia University.
MOIYA MCTIER: Oh, in the whole universe? That's tricky. So we have an idea of how many stars there are in the Milky Way galaxy. And we did that by looking at how bright different parts of the galaxy-- and we know how bright different types of stars are, so we can do some kind of math to figure out how many stars we have. And we also have an idea of how many galaxies there are in the observable universe.
And so we can just multiply the number of stars in the Milky Way by the number of galaxies that we can see. And when we do that, we get that there are about 100 billion stars in the Milky Way and 100 billion galaxies like it. Which mean there should be-- I think the number is 10 sextillion.
MOLLY BLOOM: 10 sextillion-- that's way bigger than a million, bigger than a billion, bigger than a trillion. It's the number 10 followed by 20 zeroes. So many stars.
All the stars we can see are part of the Milky Way galaxy. Moiya says a galaxy is a collection of stars, gas, dust, and dark matter that are all bound together by gravity. The Milky Way is part of a larger group of about 50 to 100 galaxies, also bound together by gravity.
MOIYA MCTIER: There are parts of the universe that we can't see, and so there are-- we don't even know how many galaxies there are in the universe, the part of the universe that we can't see. So no one can actually answer the question of how many stars there are in the whole universe.
MOLLY BLOOM: Stars come in different sizes, too. Our shining star, the sun, is a pretty average-sized star. And by average, I mean it can fit about 1 million Earths in it.
MOIYA MCTIER: There are stars that are up to, like, 50 to 100 times bigger than our sun. Those are really big ones. We call them O-type stars. They burn really hot, and they live really short lives.
But then there are also stars that can be almost 7% the size of the sun, so, like, 1/10 the size of the sun. And those are called M-dwarf stars. They're really small. They are pretty cool by comparison, only about 3,000 degrees Kelvin. And they live for a really long time. They live for trillions of years.
MOLLY BLOOM: The numbers we're talking about are so huge-- trillions of years, sextillion stars. I asked Moiya how she can think about it without hiding under a pile of pillows.
MOIYA MCTIER: In some ways, it brings me comfort, actually, to think about how huge the universe is and how tiny our entire planet is compared to the universe. [MYSTICAL MUSIC] When astronauts come back from space, they talk about something called the "pale blue dot phenomenon." And it's when you can look at the entire Earth from outside of it.
It gives you a whole new perspective on life and humanity, and it makes you really appreciate what it means to be a human living on this tiny rock, hurtling through space at thousands of kilometers per second. Which is pretty cool, I think. And it's not something you can get if you don't remove yourself from the small confines of Earth and start thinking about the large scales that space has.
MOLLY BLOOM: Before we move on, let's take a listen to a few more of your space-rific star names.
FIONA: If I discovered a new star I would name it Betelgeuse 2 because I already know there is a star named Betelgeuse, and I watched the movie Beetlejuice a million times.
ATHOS: Hi, Brains On. I would call a star God because it is in the sky.
PRIYA: What I would name a star is Magnus.
ETHAN: My star name would be Intergalactic Push-Up.
DUHA: I will call my star Star Fruit because I like to eat star fruit, and it has the word "star" in it.
JULIA: I would name my star Rosabell because Rosie and Bella are my cats names that I love so much. And Rosie and Bella combined equals Rosabell.
ZARA: If I had to name a star, I would name it Calidum Album because it's Latin for "white hot," and stars are very hot.
MOLLY BLOOM: Thanks to Fiona, Athos, Priya, Ethan, Duha, Julia and Zara for sending in those names.
[REVERSED AUDIO SOUND]
CROWD: Brains on!
MOLLY BLOOM: People around the world have been naming stars and sharing stories about them for a long time. We can see a lot of the same stars, so there are lots of different names and stories for the same parts of the night sky.
One thing lots of people have looked up at is actually a bunch of stars at once. It's light from the core of our galaxy, the Milky Way. It shows up as a hazy band in the sky. Here are a couple of names for the Milky Way from around the world.
ANNETTE LEE: [LAKOTA], and this is "the world of the spirits."
JOSE DE PRADA-SAMPER: [NON-ENGLISH], "the white ashes."
MOLLY BLOOM: That's Jose de Prada-Samper and Annette Lee. They both told us different folk tales about where the Milky Way came from. Annette's a Native American astrophysicist and artist, and her story comes from the Lakota tribe, where the Milky Way is known as the road of the spirits.
[ADVENTUROUS MUSIC]
ANNETTE LEE: So in our Indigenous way of knowing, we came here from another place, and we call this place the spirit world or the star world. Our spirits have lived really long time, and we'll keep going after this. So there's a "before this" time and a "after this" time. And so before we were here, we were in the star world.
But to get from the star world to here, there was a journey, a whole process. So the Milky Way plays an important role because it's a really big, important path. So think of-- like, you're in this forest. Instead of trees, you've got all of these stars. You have to try to find your way without getting lost.
So a path through the forest, through the stars is going to be really, really helpful. And so there's this path that we have in the sky, and that's the Milky Way. It's the road of the spirits or the path of the spirits.
MOLLY BLOOM: Jose de Prada-Samper told us another story about the Milky Way. This one is from the Southern hemisphere. He's studied a tribe of people who lived in Southern Africa.
JOSE DE PRADA-SAMPER: The !Kung people lived, and their descendents now live, in the Northern Cape province of South Africa. And in the traditional !Kung language, the name of the Milky Way is [NON-ENGLISH], "the white ashes." The name, translated, means "white ashes."
And it is a very well-known story that it was a girl who created the Milky Way. In the !Kung story, the girl is in a separate hut from that she usually lives so that her elders can teach her because she's entering a completely new period in her life. She cannot be with her family. She cannot play with her friends. And that's why she's very frustrated and very angry.
She had a nice fire, but the fire, now, is off. And she sees the beautiful ashes, white ashes there on the surface. And she picks-- with both hands, she picks the ashes. And then she throws them into the sky and says, these ashes will become the Milky Way. And she tells the ashes, you must stay in the sky so that the people see you, so that you give light to the people when they are returning home.
And because she is so powerful now, because she's undergoing this change, what she says becomes true. The ashes turn into stars, and the Milky Way begins to sail in the sky.
MOLLY BLOOM: The stars have helped people remember and share stories like these for a long time. People have also used the stars to find their way around and understand the weather and the seasons. Looking up at the vast, star-filled night sky has been important to humans for a very long time.
[JAUNTY ELECTRONIC MUSIC]
LAKEN: Stars are big balls of gas that are very far away from us.
MOLLY BLOOM: Even though they're huge, they look like tiny pinpoints of light because they're so far away.
LAKEN: The sun is the closest star to us and is the center of our solar system.
MOLLY BLOOM: Stars begin to form when clouds of dust and gas collapse.
LAKEN: Our sun is an average-sized star. Some are smaller, and some are much bigger.
MOLLY BLOOM: People have had names and stories about stars for thousands of years. That's it for this episode of Brains On.
LAKEN: It was produced by Marc Sanchez, Menaka Wilhelm, Sanden Totten, and Molly Bloom.
MOLLY BLOOM: We had production help from Christina Lopez and Amy McCann, who went to great lengths to help us record today's episode. We had engineering help from Eric Romani. Special thanks to Phil Plate and Nora McInerney.
LAKEN: Brains On is a nonprofit public radio show.
MOLLY BLOOM: You can support us and help us keep making episodes at brainson.org/fans.
LAKEN: Now, before we go it's time for our Moment of Um.
[CHORUS OF PEOPLE SAYING "UM"]
ELI: Do whales drink? And if so, how?
JOY REIDENBERG: Hi. My name is Joy Reidenberg, and I am a professor at the Icahn School of Medicine at Mount Sinai. But my research is in comparative anatomy, looking at animals adapted to extreme environments-- in particular, whales and dolphins.
Whales can drink, but they usually don't drink. And the reason for that is that the water that they're swimming in is very salty. So if they drink saltwater, then they need to get rid of the extra salt. It's more efficient for them to simply get the water from the food that they eat because there is freshwater inside the prey that they consume.
But if they do swallow some seawater by accident as they're swallowing their food, they can get rid of that extra salt because they have very special kidneys. Their kidneys look like a bunch of grapes. Each little ball of that kidney is a separate, miniature kidney.
So it looks more like they have hundreds of little kidneys rather than one big kidney, the way we do. That provides a lot of surface area in the kidney for concentrating the urine so that the water is retained and only the salts are excreted with just the smallest amount of water.
So that kind of a kidney is called a reniculate kidney, and it's only found in marine mammals and bears, interestingly. But some bears are actually marine mammals, like polar bears. They swim in saltwater, and they can do so for many days at a time. So you find that in seals and in sea lions and all of the different dolphins and porpoises as well as the big whales.
MOLLY BLOOM: OK. Who's ready to drink in this list? I know I am. It's time for the Brains Honor Roll. This is the group of listeners who keep us going by sending us ideas, questions, mystery sounds, drawings, and high fives.
[LISTING HONOR ROLL]
Brains On will be back soon with more answers to your questions.
LAKEN: Thanks for listening.
Transcription services provided by 3Play Media.
