The Sun for Kids: What Does the Sun Do and Why Is It So Important?
What does the sun do all day, and why do we need it? Explained for kids with hands-on experiments: day and night, your shadow through the day, the light race to Earth, how big the sun is and why there is summer and winter.
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More for young space fans
What does the sun do – and why do we need it?
The sun is a star
The sun is a huge, glowing ball of hot gas. In its core it's about 15 million °C (27 million °F). There, tiny hydrogen particles fuse into helium – that's called nuclear fusion. It releases so much energy that the sun has been shining for 4.6 billion years.
Don't worry, it still has plenty of fuel: the sun will keep shining for about another 5 billion years. And all the other stars in the sky are suns too, just much farther away.
The sun has lots of jobs
Light: The sun is our lamp. Without it, the Earth would be pitch dark all the time, and even the moon couldn't shine.
Warmth: It heats the Earth. Without the sun our planet would be a giant ball of ice, much colder than any freezer.
Food: Plants make their food from sunlight, water and air. Everything we eat – bread, apples, even cheese from a cow that ate grass – wouldn't exist without the sun.
Air to breathe: As plants grow, they give off oxygen. You're breathing it in right now – thank you, sun, and thank you, plants!
Weather and rain: The sun makes water evaporate from oceans and lakes. That turns into clouds, rain and snow. And wind happens because the sun warms the air more in some places than in others.
Day and night: Because the Earth spins, sometimes our side faces the sun and it's day, and sometimes the other side does and it's night where we are.
Seasons: Because the Earth's axis is tilted, we get more sunlight in summer and less in winter.
Energy: Solar panels turn sunlight into electricity. Even coal and oil are stored solar energy from plants that grew millions of years ago.
Health: When sunlight falls on your skin, your body makes vitamin D, which your bones need. But too much sun gives you a sunburn, so don't forget the sunscreen!
The sun doesn't travel around us – it's the Earth that spins, once every 24 hours. The side facing the sun has day, the other side has night. Spin the Earth and see when it's light and when it's dark where you are.
Morning: Your side of the Earth is turning into the light – the sun is rising.
Day: Your side of the Earth is facing the sun.
Evening: Your side is turning into the shadow – the sun is setting.
Night: You're on the shadow side. On the other side of the Earth it's daytime now.
Did you know? At the equator the Earth spins at about 1,670 km/h (1,040 mph). You don't notice because everything around you spins along – the air, the houses and you too.
When the sun is high in the sky, your shadow is short. When it's low, your shadow gets as long as a giant's. Move the time and watch your shadow grow and shrink today.
The sun has set – now you have no sun shadow.
The shadow rule
If your shadow is shorter than you are, the sun is high and especially strong. Time for sunscreen, a hat and some shade!
Light is the fastest thing in the whole universe: 300,000 km (186,000 miles) per second. In a single second it could zoom around the Earth seven and a half times. Even so, it takes more than 8 minutes to get from the sun to us. Who wins the race to Earth?
Imagine the light leaves the sun right now. This is how long it takes to reach you:
Arrived! So the sun you see is always a little over 8 minutes old.
When the light arrives, this is how far the others have come:
Worked out for the average distance of 93 million miles (149.6 million km), nonstop and without refueling: space probe 430,000 mph, rocket 25,000 mph, airplane 560 mph, car 62 mph (100 km/h), bicycle 9 mph, snail 55 yards an hour.
The sun is so enormous that 109 Earths fit side by side across it. About 1.3 million Earths would even fit inside it. Drag the slider and line up Earths across the sun.
If the sun were a soccer ball
If the sun were the size of a soccer ball, the Earth would be a pinhead 24 meters (80 feet) away. The moon would be a grain of sand, a little over 2 inches from the Earth.
An amazing coincidence
The sun is about 400 times wider than the moon, but also about 400 times farther away. That's why both look almost the same size in the sky – and the only reason the moon can cover the sun exactly during a solar eclipse.
The Earth's axis is a little tilted, by 23.4 degrees. So on its trip around the sun, sometimes the Northern Hemisphere leans toward the sun and sometimes the Southern Hemisphere does. Whoever leans toward the sun has summer: the sun climbs higher, shines longer and warms more strongly.
By the way: in early January the Earth is closest to the sun! So distance doesn't make the seasons – the tilt does.
Important: never look straight at the sun!
The sun is so bright that it can damage your eyes forever – even with sunglasses, and even more so with binoculars or a telescope. For solar eclipses there are special eclipse glasses.
Watch the sun with the pinhole trick
Poke a small hole in a piece of cardboard with a pin. Stand with your back to the sun and hold the cardboard so that the light falls through the hole onto a white sheet of paper. A small picture of the sun appears there. During a solar eclipse you can even see the nibbled sun this way!
What if the sun went out?
Don't worry, that won't happen! But just imagine: we would only notice after about 8 minutes, because the last light would still be on its way. Then it would get dark, and shortly afterwards the moon would disappear too – it only shines with borrowed sunlight.
Questions about the sun
How hot is the sun? Its surface is about 5,500 °C (10,000 °F), its core about 15 million °C (27 million °F). For comparison: an oven reaches about 250 °C (480 °F).
How far away is the sun? 93 million miles (149.6 million km) on average. In early January it's a bit closer at about 91 million miles, in early July a bit farther at about 94.5 million miles.
Why is the sun round? Gravity pulls all the gas evenly toward the middle. That makes a ball – which is also why the Earth and the other planets are round.
Why is the sun red in the morning and evening? When it's low, its light has to travel a long way through the air. Along the way the blue light is scattered to the side, and yellow, orange and red are left.
Will the sun ever go out? In about 5 billion years it will swell into a red giant and then slowly cool down as a small white dwarf. There's an unimaginably long time until then.