# What is a supernova?

An episode of [Science for Kids / Science's Not Boring: The Kids Science Podcast](https://invisiblenetwork.ai/podcast/1896928296), 11 Oct 2026, 11 min.

Audio: https://www.buzzsprout.com/2624612/episodes/19906091-what-is-a-supernova.mp3

Have you ever wondered what happens when a giant star reaches the end of its life? Boom! It explodes in one of the most powerful and spectacular events in the entire universe—a supernova! Join Mira and Finn on Science's Not Boring as we blast off to discover the amazing secrets of exploding stars! Did you know that a single supernova can shine brighter than a hundred billion stars combined? We’ll travel back in time to the year 1054 when Chinese astronomers saw a massive explosion so bright it could be seen in the daytime sky for 23 days straight! You’ll learn how stars are like giant games of tug-of-war between gravity and nuclear energy, and what happens when their core turns into iron. Plus, discover mind-blowing facts about what’s left behind! Imagine a neutron star so squished and heavy that just one single teaspoon of it weighs a billion tons! Get ready to find out how these epic space explosions actually created the ingredients that make up the Earth, and even you. We are literally made of stardust! Tune in for an out-of-this-world adventure!

## Transcript

[0:00] SPEAKER_00: Welcome to Sciences Not Boring by Kidopoly.com.
[0:03] SPEAKER_00: I'm Mira! And I'm Finn! A big hello to Grey, who asked to learn more about the Crab Nebula, and who told us it exploded less than a thousand years ago and could be seen in the daytime.
[0:16] SPEAKER_00: This one is for you.
[0:17] SPEAKER_01: And a big hello to Amelia and Inez in Connecticut, who love listening on the way to piano lessons.
[0:23] SPEAKER_00: If you haven't already, tap follow wherever you're listening so you never miss an episode.
[0:29] SPEAKER_01: So, Mira, Grey mentioned an explosion in space.
[0:33] SPEAKER_01: Are we talking about stars blowing up?
[0:36] SPEAKER_00: We absolutely are! Imagine an explosion so massive, so incredibly bright, that for a few short weeks it outshines an entire galaxy of a hundred billion stars combined.
[0:50] SPEAKER_01: Wait, one single explosion can outshine a hundred billion stars?
[0:56] SPEAKER_00: Exactly! It blasts out pieces of itself at 30,000 kilometres per second.
[1:02] SPEAKER_00: That is 10% of the speed of light.
[1:05] SPEAKER_01: 30,000 kilometres a second?
[1:08] SPEAKER_01: You could travel all the way around the entire Earth in just over one second.
[1:13] SPEAKER_00: You got it! Today we are exploring one of the most violent and spectacular events in the entire universe.
[1:20] SPEAKER_00: We're talking about supernovas.
[1:23] SPEAKER_01: Okay, I know what a star is, like our sun, but why would one just suddenly blow up?
[1:29] SPEAKER_00: To understand the explosion, we have to understand how a star lives.
[1:34] SPEAKER_00: A star is basically a giant glowing ball of hot gas, mostly hydrogen and helium.
[1:41] SPEAKER_01: And they burn really hot, right?
[1:43] SPEAKER_01: Like millions of degrees.
[1:45] SPEAKER_00: Way hotter.
[1:47] SPEAKER_00: The core of our Sun sits at around 15 million degrees Celsius.
[1:52] SPEAKER_00: At those extreme temperatures, the star acts like a giant nuclear reactor.
[1:57] SPEAKER_01: 15 million degrees?
[2:00] SPEAKER_01: That would instantly melt any spaceship we sent there.
[2:03] SPEAKER_00: Oh, absolutely.
[2:05] SPEAKER_00: But here is the secret to a star's life: it's a giant game of tug of war.
[2:11] SPEAKER_00: Gravity is pulling all that massive gas inward, trying to crush the star.
[2:16] SPEAKER_01: So why doesn't it just squish into a tiny ball right away?
[2:20] SPEAKER_00: Because of the nuclear reactions in the core.
[2:23] SPEAKER_00: They create an enormous amount of energy that pushes outward.
[2:27] SPEAKER_00: So gravity pulls in, energy pushes out, and the star stays perfectly balanced.
[2:33] SPEAKER_01: Oh, so as long as it has fuel to burn, it stays perfectly round and stable.
[2:38] SPEAKER_00: Exactly.
[2:40] SPEAKER_00: But our sun is just an average-sized star.
[2:43] SPEAKER_00: Some stars are monsters.
[2:45] SPEAKER_00: I'm talking about supergiants that are 8 to 50 times heavier than our Sun.
[2:51] SPEAKER_01: 50 times heavier?
[2:53] SPEAKER_01: I bet those huge stars have a ton of fuel, so they live forever, right?
[2:57] SPEAKER_00: Actually, the opposite.
[2:59] SPEAKER_00: Massive stars live fast and die young.
[3:03] SPEAKER_00: Because they are so heavy, gravity squeezes their cores so hard that they have to burn through their fuel at furious speeds just to hold themselves up.
[3:12] SPEAKER_01: So what happens when these giant stars run out of their normal hydrogen fuel?
[3:17] SPEAKER_00: They start combining heavier and heavier elements to stay alive.
[3:21] SPEAKER_00: They make helium, then carbon, neon, oxygen, and silicon.
[3:26] SPEAKER_00: The star looks like an onion, with layers of different elements burning all at once.
[3:31] SPEAKER_01: An onion star! That sounds almost delicious, but probably too spicy.
[3:37] SPEAKER_00: Definitely too spicy.
[3:39] SPEAKER_00: But eventually, the star reaches the end of the line.
[3:42] SPEAKER_00: The very centre of the core turns into iron, and iron is bad news for a star.
[3:48] SPEAKER_00: Why is iron bad?
[3:49] SPEAKER_00: Isn't iron super strong?
[3:51] SPEAKER_00: It takes more energy to burn iron than it gives back.
[3:54] SPEAKER_00: Suddenly, the outward push stops.
[3:57] SPEAKER_00: The tug of war is over.
[3:58] SPEAKER_00: Gravity wins instantly.
[4:00] SPEAKER_01: Wait, so without the outward push, what happens to all that gravity pulling millions of miles of gas inward?
[4:07] SPEAKER_00: In a fraction of a second, the entire star collapses on itself.
[4:11] SPEAKER_00: The core itself rushes inward at almost a quarter of the speed of light.
[4:16] SPEAKER_00: The whole star falls inward.
[4:18] SPEAKER_00: That's terrifying.
[4:19] SPEAKER_00: They slam into the iron core so hard that the temperature spikes to 100 billion degrees.
[4:25] SPEAKER_00: It gets so squeezed that it physically can't compress anymore, so it rebounds like a cosmic trampoline.
[4:32] SPEAKER_00: Oh, so all that material bounces back outward?
[4:35] SPEAKER_00: Yes, an unimaginably powerful shockwave rips outward, tearing the star completely apart.
[4:42] SPEAKER_00: Boom! That is the supernova explosion.
[4:45] SPEAKER_00: And this is exactly what our listener Grey was talking about with the Crab Nebula! Grey, your facts are totally spot on.
[4:53] SPEAKER_00: When did the Crab Nebula supernova happen?
[4:56] SPEAKER_00: The light from that specific explosion reached Earth on July 4th in the year 1054, over 972 years ago.
[5:06] SPEAKER_00: Wow! Did scientists back then see it?
[5:09] SPEAKER_00: They sure did.
[5:11] SPEAKER_00: Chinese astronomers recorded seeing what they called a guest star.
[5:15] SPEAKER_00: It was so incredibly bright that it was visible in the daytime sky for 23 days straight.
[5:22] SPEAKER_01: In the daytime?
[5:24] SPEAKER_01: Like right next to the sun?
[5:26] SPEAKER_01: That is unbelievable! How far away was it?
[5:30] SPEAKER_00: It was 6,500 light years away.
[5:33] SPEAKER_00: To be that far and still visible during the day just proves how monstrous a supernova really is.
[5:40] SPEAKER_01: So after the star blows itself to pieces, is anything left behind?
[5:44] SPEAKER_01: Or is it just an empty spot in space?
[5:47] SPEAKER_00: Oh, something amazing is left behind.
[5:50] SPEAKER_00: The blown-off outer layers become a beautiful glowing cloud of gas called a nebula.
[5:56] SPEAKER_00: But that squished iron core, it becomes a neutron star.
[6:00] SPEAKER_00: A neutron star?
[6:02] SPEAKER_00: How big is that?
[6:03] SPEAKER_00: It is tiny, only about 20 kilometres across.
[6:07] SPEAKER_00: You could fit it inside a big city.
[6:10] SPEAKER_00: But because it was crushed by an entire star's gravity, it is incredibly dense.
[6:15] SPEAKER_01: Wait, an entire star squished into the size of a city?
[6:19] SPEAKER_01: How heavy is that?
[6:21] SPEAKER_00: Hold on to your headphones, Finn.
[6:23] SPEAKER_00: Just one single teaspoon of a neutron star weighs one billion tonnes.
[6:28] SPEAKER_00: That is like putting over 2,000 skyscrapers into a tiny spoon.
[6:33] SPEAKER_01: A billion tons in a teaspoon?
[6:35] SPEAKER_01: That would crush through the earth like a cannonball!
[6:39] SPEAKER_00: It totally would! But beyond the crazy extreme science, supernovas are actually the reason you and I are sitting here today.
[6:48] SPEAKER_01: What do you mean?
[6:49] SPEAKER_01: How did exploding stars create us?
[6:52] SPEAKER_00: The Big Bang mostly created hydrogen and helium.
[6:56] SPEAKER_00: Almost every other element in the universe was forged inside a star, or in the extreme heat of a supernova explosion.
[7:05] SPEAKER_01: So all the stuff on Earth dirt, rocks, water, metals?
[7:10] SPEAKER_00: Yep.
[7:11] SPEAKER_00: The calcium in your bones, the iron in your blood, the oxygen we breathe, and the magnesium in rocks.
[7:18] SPEAKER_00: They were all blasted into space by supernovas billions of years ago.
[7:23] SPEAKER_01: So when the famous scientist Carl Sagan said, we are made of star stuff, he wasn't just being poetic.
[7:30] SPEAKER_01: It's actually a literal scientific fact.
[7:33] SPEAKER_01: Exactly!
[7:34] SPEAKER_00: We are walking, talking stardust.
[7:37] SPEAKER_00: And here's another wild fact.
[7:39] SPEAKER_00: The universe is so vast that a supernova explodes somewhere out there every 10 seconds.
[7:47] SPEAKER_00: Every 10 seconds?
[7:49] SPEAKER_00: Will one explode near us soon?
[7:51] SPEAKER_00: Don't worry, there are no stars close enough to Earth to hurt us if they go supernova.
[7:56] SPEAKER_00: But there is a famous red supergiant called Beetlejuice.
[8:00] SPEAKER_00: The scientists are watching closely.
[8:03] SPEAKER_00: It could explode tomorrow or a hundred thousand years from now.
[8:07] SPEAKER_01: Alright Finn, time for the quiz.
[8:09] SPEAKER_01: Are you ready?
[8:10] SPEAKER_01: Okay, my brain is full of star stuff, but I'm ready.
[8:14] SPEAKER_00: Okay, first question.
[8:16] SPEAKER_00: How many days was the Crab Nebula supernova visible during the daytime?
[8:25] SPEAKER_00: Next one.
[8:26] SPEAKER_00: What specific element builds up in the star's core right before it collapses?
[8:35] SPEAKER_00: Question three.
[8:36] SPEAKER_00: According to what we learned, how much would a teaspoon of a neutron star weigh?
[8:45] SPEAKER_00: Alright, here's number four.
[8:47] SPEAKER_00: What speed does the supernova shockwave travel when it blasts outward?
[8:56] SPEAKER_00: Last question.
[8:57] SPEAKER_00: Who recorded seeing the supernova of 1054 as a guest star?
[9:06] SPEAKER_00: Great job! Let's see how you did.
[9:09] SPEAKER_00: The first answer is it was visible for 23 days.
[9:13] SPEAKER_00: For question 2, the core turns into iron before collapsing.
[9:18] SPEAKER_00: For number 3, a single teaspoon weighs 1 billion tonnes.
[9:24] SPEAKER_00: Question 4.
[9:25] SPEAKER_00: The shockwave travels at a whopping 30,000 kilometers per second.
[9:31] SPEAKER_00: And the final answer is, Chinese astronomers recorded it in the year 1054.
[9:36] SPEAKER_01: Mirror.
[9:37] SPEAKER_01: I don't think I'll ever look up at the night sky the same way again.
[9:41] SPEAKER_01: Knowing that some of those dots might explode, and that their explosions made our world.
[9:47] SPEAKER_01: It's just mind-blowing.
[9:49] SPEAKER_01: I totally agree, Finn.
[9:51] SPEAKER_00: Science is all about making us see the universe in a whole new, wonderful light.
[9:56] SPEAKER_00: Hey everyone!
[9:57] SPEAKER_01: If you loved learning about supernovas, please give us a five-star review, just like the millions of stars we talked about today.
[10:04] SPEAKER_01: Just scroll down and tap the stars.
[10:06] SPEAKER_00: Tap follow on this show so you never miss out.
[10:09] SPEAKER_00: And check out our sister shows.
[10:11] SPEAKER_00: History and philosophy's not boring, and maths is not boring.
[10:16] SPEAKER_00: Go give those a listen and a follow as well.
[10:18] SPEAKER_01: And if you want to shout out on the show or just want to say hi, email us at hello at kidopoly.com.
[10:25] SPEAKER_00: Thanks for exploring the cosmos with us.
[10:27] SPEAKER_00: See you next time on Science is Not Boring.
[10:30] SPEAKER_00: Bye!

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