The quick answer
The Sun is a star, a giant ball of very hot gas. Deep in its centre, tiny bits of gas are squeezed together so hard that they join up. This makes huge amounts of light and heat.
TankiRanki, the Sun shines all day long. Doesn’t it ever get tired?
RankiHa, the Sun never needs a nap. Its secret is hidden deep inside. Let’s find out!
The Sun is a star
The Sun looks like a yellow circle in the sky. But it is really a star, just like the stars you see at night. It looks much bigger and brighter because it is much closer to us.
The Sun is not solid like the Earth. It is a giant ball of very hot gas. Most of this gas is called . Another gas, called , makes up most of the rest.
A giant squeeze in the middle
The middle of the Sun is called the . It is the hottest place in our whole . A solar system is a star with all the planets that travel around it. Scientists think the core is about 15 million degrees Celsius.
The Sun is so big and heavy that it squeezes its core very hard. Tiny bits of hydrogen crash into each other at great speed. Sometimes they stick together and turn into helium. Scientists call this .
Each time bits join together, a little is set free. Energy is what makes things move, glow or warm up. In the core, this happens a huge number of times every second. All that energy slowly travels outwards and leaves the Sun as light and heat.
- Hydrogen bits are squeezed together in the core.
- They join up and become helium.
- Each join sets free a little energy.
- The energy shines out as light and heat.
TankiSo the Sun is a giant fire in the sky?
RankiNot quite. A fire burns things up. The Sun squeezes things together instead.
How big and how far?
The Sun is huge. About 109 Earths would fit across its middle, like beads on a string. If the Sun were a hollow ball, about 1 million Earths could fit inside.
The Sun is about 150 million kilometres away from us. That is so far that its light needs about 8 minutes to reach the Earth. So the sunshine on your face left the Sun about 8 minutes ago.
Keep your eyes safe
The Sun is so bright that it can hurt your eyes. Never look straight at the Sun, not even with sunglasses. Never look at it through binoculars or a telescope either. Watching shadows is a much safer way to have fun with sunlight.
The Sun is very important for life on Earth. Its light helps plants grow, and its heat keeps our planet warm. Without it, there would be no day, no summer and no food.
Try it
Track a shadow on a sunny day
You need
What to do
- Go outside with a grown-up on a sunny morning.
- Stand the stick up in the clay on flat ground.
- Mark the tip of the stick’s shadow with chalk or a pebble.
- Come back every hour and mark the shadow again.
- Look at your marks. How did the shadow move and change?
- Remember to look at the shadow, never at the Sun.
Ask a grown-up to help you with this one.
TankiSo the Sun shines because it squeezes hydrogen into helium. No naps needed.
RankiExactly. It has been shining for billions of years, and it will keep going for billions more.
Big words
- hydrogen
- The lightest gas there is. The Sun is mostly made of it.
- helium
- A light gas. The Sun makes it from hydrogen.
- core
- The very middle of the Sun, where it is hottest.
- nuclear fusion
- When tiny bits are squeezed so hard that they join and give off energy.
- energy
- What makes things move, glow or warm up.
- solar system
- The Sun and all the planets and other things that travel around it.
Quick quiz
1. What is the Sun?
The Sun is a star, a giant ball of very hot gas.
2. What happens in the Sun’s core?
In the core, hydrogen bits join up into helium and set free energy.
3. How long does sunlight take to reach the Earth?
The Sun is about 150 million kilometres away, so its light needs about 8 minutes.
For parents and teachers
In the Sun’s core, hydrogen nuclei fuse into helium and a tiny amount of mass is turned into a huge amount of energy. A good talking point is the difference between burning and fusion, and how sunlight drives weather, plant growth and in the end almost all our food.
Pictures marked “AI generated” were made with AI tools. Ranki and Tanki are AI generated characters. Found a mistake? Write to info@pr-geo.com and we will fix it.
