Top 100 Cool Science Facts for Kids!

The World of Wonder

Why is the sky blue? What is air made of? How many stars are there?
World of wonder fun science facts that every child should know! This article covers space, nature, technology, engineering, elementary math, chemistry, physics and biology.
Science is fascinating and tries to explain how everything in the world and outer space works. Science gives us the answers to questions like "What is electricity?" and "How does an aeroplane fly?" Read on and learn 100 more cool science facts!

1. Which Is Heavier, a Ton of Feathers or a Ton of Coal?

This is a trick question and lots of people get caught out. Of course they both have the same weight! However coal is denser than feathers which means a lot of weight is packed into a smaller space or volume. Feathers are less dense than coal but take up lots more space for the same weight.

2. Why Is the Sky Blue?

Visible light from the Sun is made up of different colours, in fact all the colours of the rainbow. These colors have different wavelengths. Blue is one of these colours and has a short wavelength. The atmosphere is made up of different gasses we call air, composed of tiny particles called molecules. It also has lots of tiny water droplets floating in it. Blue light can't pass straight through these droplets to our eyes but gets reflected or bounced and scattered backwards and forwards by the gas molecules and droplets, eventually coming out of the sky. The effect is that the sky gets lit up in a blue color.

3. Why Do Ships and Ice Float?

The Principle of Archimedes explains why ice floats. This says that the force or push upwards on an object equals the weight of displaced water. Displaced means pushed out of the way. Since ice is less dense than water, the weight of a piece of submerged ice would be less than the weight of water it displaces. So the force upwards is greater than the weight acting downwards and the ice gets pushed to the surface. Ships float also because they displace a lot of water.

4. Can We Travel to the Centre of the Earth?

Most of the inside of the Earth is made of really hot melted rock. This part is called the mantle. At the centre of the Earth is the core which is made of solid iron. It would be really difficult to travel to the Earth's centre because it is so far away and all the material would have to be pushed out of the way as we travel. The distance to the centre is nearly four thousand miles. Even building tunnels 20 miles long takes many, many years. Some of the deepest mines are only 2 1/2 miles deep.

5. Why Can Birds Sit on Power Lines and Not Get a Shock?

Electricity flows around in a loop. When a bird lands on a power line, electricity can't flow through its body. However if it touched an adjacent line with a lower voltage, electricity would flow from one line through its body to the other line and it could be electrocuted.

6. Why Are Things Different Colors?

White light is made up of lots of colors. In fact, all the colors of the rainbow: red, orange, yellow, green, blue, indigo and violet. When white light falls on an object some of it is reflected just like the way a ball bounces off a wall. Other colors in the light are absorbed or taken in by the object and not let back out. So a red object for instance absorbs all colors except red which is reflected. When this red light reaches our eyes we perceive the object as being red. Perceive means how our brain interprets or decides on what is outside our bodies from the information we experience with our five senses. These senses are smell, sight, taste, touch and hearing.

7. What Is Sound?

Sound is a vibration of air molecules. When you hit something, it shakes or vibrates really quickly. This shakes the air all around it. The air next to this air also shakes and the shaking continues just like a string of people in a line passing on a message to each other. Sound propagates or travels through the air and eventually we hear it. Sound can also travel through a solid or liquid. Sound has an amplitude and frequency. The amplitude is a measure of the strength of the waves. The frequency is how quickly the sound vibrates

8. Can We Hear in Space?

No, we can't because there is no air in space. We call this a vacuum. Without air, vibrations produced by an object or when we speak can't be transmitted through space.

9. How Do We Talk to Astronauts in Space?

We can't use sound because it doesn't travel through the vacuum of space and in any case, it wouldn't go far enough. We have to use radio communication. Our voice is turned into electricity by a microphone and then into radio waves or electromagnetic radiation. These waves travel really fast, in fact a signal would go around our planet Earth seven times in one second. When the waves get to the astronauts spacecraft, they are turned back into electricity and sound by a loudspeaker or headphones.

10. Why Are Leaves Green?

Leaves contain a chemical called chlorophyll. This chemical turns the gas carbon dioxide or CO2 into stored energy in the plant. All the wood in a big tree comes from carbon dioxide taken out of the air.

Recommended

Emily Dickinson's "There is a morn by men unseen"

11. What Is a Light Year?

A light year is the distance light travels in a year. Light travels at a speed of approximately 186,000 miles per second. So in one second it could travel around our planet at the equator over 7 times! In a year, there are 31,536,000 seconds, so the distance light travels is about six million million miles (6 trillion miles). That's 6 with 12 zeroes after it. Light years are used to describe how far away stars are because the number in miles would be too long to write down.

12. How Far Is the Nearest Star?

Our nearest star is Proxima Centauri, a red dwarf star just a little over 4 light years away. That's 24 trillion miles. Our Sun is also a star, but it is still really, really far away, in fact 93 million miles. Some stars are so far away that it takes light millions of years to reach us, so we see the stars as they were millions of years ago.

13. How Long Would It Take To Get to the Sun if an Airplane Could Fly There?

There isn't any air in space so an airplane couldn't fly to the Sun, but if it could, it would still take over 20 years.

14. How Many Stars Are There?

We have estimated that there are 300 sextillion stars. That's 3 followed by 23 zeroes or 300 thousand million, million, million.

This is how we would write that number:
300,000,000,000,000,000,000,000

It is said that there are more stars in the Universe than there are grains of sand on all the beaches of the world. Stars are grouped into clusters called galaxies that can contain one trillion stars. There are estimated to be 100 billion galaxies in the Universe.

15. What Is Electricity?

Electricity is the flow of tiny particles called electrons. In some materials such as metals, electrons are not held tightly to atoms and are free to wander. When a voltage is applied to the material, it forces the electrons to flow along it. This flow of electrons is called a current and is measured in amps.

If you would like to know more about electricity, you can read all about it here:
Watts, Amps and Volts Explained — Kilowatt Hours (Kwh) and Electrical Appliances

16. What Is Lightning?

When clouds get charged up with electricity during a thunderstorm, the voltage eventually gets too high and the charge has to drain away to the ground. We call this lightning and it's like a giant spark. The sound produced by lightning is called thunder. We hear thunder after we see lightning because light from the flash travels faster to our eyes than the sound. If lightning is far away, it can take many seconds to hear the thunder. The spark in the spark plug of a car is like a mini version of lightning.

17. What Is Air Made Of?

Air is a gas, but it's not just one gas, it's a mixture of lots of different types. Most of the air though is made up of the gasses nitrogen, oxygen and carbon dioxide.

18. Is Air Heavy?

A cube of air one metre wide (39 inches) by one metre long by one metre high weighs about 1 1/4 kilograms or 2 3/4 pounds.