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My name is Sandeep.
I am from Bengaluru, India and you're listening to Sleep Tight Science.
Did you know your body gives off tiny amounts of light all the time?
What?
It's far too faint for your eyes to see, but sensitive scientific cameras have detected it.
Right now, you are glowing.
Hello friends and welcome back to Sleep Tight Science a bedtime show that answers your questions about science.
We're taking a short break from our current series tonight to do something we always love a fun facts episode.
We have three lists with three different topics.
We'll start with some surprising facts about the human body.
Then we'll learn about the animal kingdom, where things get a little strange.
And then we'll zoom all the way out to outer space.
We will be covering a lot of different things.
Some of these facts you'll want to keep.
A few of them will change how you picture something.
And at least one of them will make you want to tell someone tomorrow.
And don't forget, if you have any ideas or topics you would like us to cover.
We always read and respond to all your suggestions that you send via email.
A quiet thank you to Sanvi from Bengaluru, India, for introducing our show.
And to all of you listening, we're very glad you're here.
Now, take a slow, deep breath in.
And let's get started with our first list.
Before we zoom off into outer space, let's start close to home with some facts about your body.
Your body is doing remarkable things at this exact moment.
Things you never asked it to do.
Things you'll never need to think about.
You might find some of these surprising.
We already mentioned the glow.
Your body produces a tiny amount of light through chemical reactions happening in your cells.
It pulses very slightly, brightest in the late afternoon, faintest while you sleep.
You can't see it, and neither can anyone else.
But instruments sensitive enough to detect it have picked it up.
You are, in the most literal sense, luminous.
Did you know your stomach grows a brand new lining every few days?
The acids inside your stomach are strong enough to help dissolve food, so your body constantly replaces the inner surface to protect itself.
For a long time, scientists believed the human nose could detect about 10,000 different smells.
That number was in textbooks, in magazines, in all kinds of places.
The problem is, it was never actually tested.
Someone said it, it got repeated, and it stuck.
Then, in 2014, researchers at Rockefeller University ran proper experiments and now think the number may be closer to one trillion.
That's a million millions.
Your nose is far more capable than anyone gave it credit for.
Did you know your brain cannot feel pain?
It processes pain signals from every other part of your body.
It is the whole reason you feel pain at all. but the brain itself has no pain receptors of its own.
This is actually why brain surgeries can sometimes be performed while the patient is awake.
The skull and surrounding tissue are numbed, but the brain doesn't need to be.
99.9% of every person's DNA is identical.
All the things that make you look and sound and seem like you your height, your hair, the way you laugh come from that remaining 01.
Your left lung is about 10% smaller than your right.
It's not a design flaw.
That space is taken.
Your heart sits slightly to the left, and your left lung simply makes room for it.
The two of them have been sharing that space since before you were born.
Did you know that you lose tiny pieces of skin all day long?
In fact, a surprising amount of the dust in your home is made from old skin cells your body has naturally shed and replaced.
That's kind of yucky.
And finally, did you know that eating a small piece of cheese at the end of a meal can help protect your teeth?
Cheese helps neutralize the acids that build up in your mouth after eating, which reduces the chance of tooth decay.
Now, let's learn a bit about the animal kingdom, where things can get a little strange.
Animals solve problems in ways that seem almost impossible, until you learn how.
And some of them have bodies that make yours look, well, a little ordinary by comparison.
Did you know that tarantulas can't grow the way you grow?
Your skeleton is on the inside, and it grows with you.
A tarantula skeleton is on the outside a rigid shell called an exoskeleton, and it doesn't grow at all.
So, periodically, a tarantula has to shed the whole thing.
It crawls out of its old exoskeleton like someone peeling off a tight suit.
And during that process, a tarantula can replace the lining of some of its internal organs.
It can also regrow legs it may have lost.
It emerges from the old shell with a new body, soft at first, hardening over hours or days.
The old exoskeleton it left behind looks so complete that people sometimes think they've found a second tarantula.
Naked mole rats are small, wrinkled, nearly hairless rodents that live underground in East Africa.
And they are amazing.
Most rodents live two or three years.
A naked mole rat can live up to 30 years.
That makes them among the longest living rodents on Earth, by a significant margin.
Scientists are genuinely interested in how they do it, and what it might tell us about aging.
Also, their teeth are something else entirely.
A naked mole.
Rat's front teeth sit outside its lips and they can move each tooth independently of the other, a bit like operating a pair of chopsticks.
They use them to dig through hard soil, chew through roots and carry things.
Two teeth working separately under full control.
Did you know that though polar bears look white, their fur though is not white at all.
Each hair is actually hollow and colorless.
And it's the way light bounces through those hollow shafts that makes the coat appear white or yellowish.
Underneath all that fur, a polar bear's skin is black, which helps absorb heat from the sun.
Did you know ladybugs are actually beetles?
The ones with the red shells and the black spots belong to a family called coccinylidae.
That's a great word.
And they are proper beetles.
Wings and all.
The shell you see is actually a hardened pair of wing covers.
Underneath, folded away, are real flying wings.
And sheep have rectangular pupils.
Most animals with eyes built for wide open spaces have evolved pupils shaped to give them the broadest possible view.
A sheep's rectangular horizontal pupil gives it a field of vision close to 360 degrees close to all the way around without moving its head at all.
A useful thing to have when you are a sheep.
And now, let's put on our spacesuits, climb into our spaceships, and zoom out.
All the way out.
Space is full of facts that make the universe feel bigger and stranger than you thought it was five minutes ago.
These ones are our favorites.
Did you know that the footprints left on the moon by the Apollo astronauts are still there?
Every single one.
The moon has no wind, no rain. no weather of any kind to disturb them.
Those boot prints pressed into the lunar dust in 1969 will still be sitting there perfectly preserved millions of years from now, long after almost everything else we've ever made has crumbled or rusted or faded away.
Those footprints will remain.
Astronauts living on the International Space Station grow taller.
Without gravity compressing the spine all day.
The fluid-filled cushions between the vertebrae, the small bones that stack to make your backbone expand slightly.
Astronauts can gain up to 5 centimeters, about 2 inches in height, during a long stay.
They shrink back down once they return to Earth and gravity gets back to work.
But for a while up there, they are genuinely, measurably taller.
Did you know that if you were standing on Mars and watched the sun go down, the sunset would be blue?
During the day, the Martian sky is a dusty reddish brown, tinted by fine iron-rich particles in the atmosphere.
But at sunset, when sunlight passes through more of that atmosphere at a low angle, the scattering works differently and the horizon glows a pale, soft blue.
Earth sunsets are red and orange.
Mars sunsets are blue.
The two planets swapped.
Saturn is the least dense planet in our solar system.
In fact, it is so low in density that if you could find a bathtub large enough and this would prove pretty challenging I guess Saturn would float.
The entire planet, rings and all, is less dense than water.
Deep inside Neptune and Uranus, scientists believe it rains diamonds.
The extreme pressure at those depths pressures far beyond anything on Earth can compress carbon atoms into diamond crystals, which then fall through the planet's interior like the most extraordinary rain imaginable.
And Mars is home to the tallest mountain in the entire solar system.
Olympus Mons is a volcano, and it stands about 22 kilometers high, or roughly 72,000 feet.
Mount Everest, the tallest mountain on Earth, reaches about 8,800 meters, or just under 29,000 feet.
Olympus Mons is nearly three times taller.
It is so wide that if you were standing at the base...
The peak would be beyond the horizon.
You wouldn't even know you were on a mountain.
Here's a wave to some of our question askers.
Fitzgerald Butler, 4 years old from Brandon, Mississippi.
Xavier, 7 years old from Dorval, Quebec.
Paige, 10 years old in Toronto, Ontario.
Knox, 6 years old from Montreal, Canada.
Corin, age 8, from the Scottish Borders.
Remi.
Aspen, age 6, from Japan.
Cole, 7 years old.
Amanda.
Arthur Granary, who just turned 5.
Rhett Fielder, Lukey, four years old, listening from Philadelphia, Pennsylvania.
Harper, seven years old, from Oakville, Ontario.
Zahar Saad, nine years old, from Mississauga, Ontario.
And Eleanor.
Eleanor.
Thank you for asking questions that spark our curiosity and keep us learning.
To submit your questions.
Ask your parents to help you.
Write us a note to the email address in our episode notes.
You can also visit our website and send a message that way.
Also, don't forget to leave us a review.
It helps other people find our show.
In this episode, we took a break from our current series to explore three lists of fun facts.
We learned that the human body glows faintly, that your nose can distinguish closer to one trillion smells than the 10000 people used to think, and that your left lung makes room for your heart.
In the animal kingdom.
We discovered that tarantulas can regrow legs and replace internal organs when they shed their skin.
That naked mole rats can live 30 years and operate their teeth like chopsticks.
And that a polar bear's skin is black.
And out in space.
We found that Apollo astronauts' footprints on the moon will last for millions of years, that Martian sunsets are blue and that it rains diamonds inside Neptune and Uranus.
Close your eyes if you like and let your shoulders soften.
Somewhere on the moon, a boot print is sitting in the dust.
Perfectly still.
No wind to shift it.
No rain to wash it away.
It has been there for more than 50 years and it will be there long after tonight, long after all of us.
In the soil somewhere in East Africa, a naked mole rat is making its way through the dark.
Busy, unhurried, those remarkable teeth working away.
And right here in this room, your body is glowing, faintly the way it always does.
Chemical reactions in your cells doing what they've always done while you rest.
Take a slow breath in and let it drift out.
From our little corner of the world, we're glad you spent this time with us.
From Cheryl and Clark, good night.
Sleep tight grown-ups.
Thank you for being here.
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