Eugene is a qualified control/instrumentation engineer Bsc (Eng) and has worked as a developer of electronics & software for SCADA systems.
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! Covering space, nature, technology, engineering, elementary math, chemistry, physics and biology. Science is fascinating and tries to explain how everything around us 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.
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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.
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:
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.
19. Which Gas Do We Breathe?
We breathe air into our lungs and use the oxygen in it. Oxygen combines with glucose in the food we eat to provide us with energy that keep us warm and makes our muscles and internal organs work. Our body makes carbon dioxide gas as a waste product and we breathe this out.
20. Is There Air on the Moon?
No, and that's one of the reasons Apollo astronauts had to wear spacesuits that supplied them with oxygen. Other planets such as Mars have an atmosphere, but the atmosphere of Mars has much less oxygen than we have on the Earth.
21. Is There Air on the Sun?
No, and the Sun isn't solid like the Earth. The Sun is made of hydrogen and helium which are gasses. These get really hot because the enormous gravity on the Sun is so strong that atoms get squashed together producing nuclear fusion. This makes lots of heat and light that will last for billions of years.
22. What is Gravity?
Gravity is the force of attraction between all objects in space. Even your body has gravity, but it's so small, the force wouldn't attract anything and make it stick. The force of attraction of a magnet is much greater. Gravity is what makes things fall and gives things weight. It also keeps the Moon close to our Earth. Without gravity, the Moon would fly off into space. Gravity also prevents our planet from moving away from the Sun.
23. What is a Force?
A force is like a push or pull. When you push or pull something, you are exerting a force. Exert is another word for apply. The force of air on the underside of an aeroplane's wing gives it lift and makes it fly. A magnet exerts a force on a piece of iron, pulling it. The wheel of a car pushes on the ground and the force on the axle moves the car forwards. When you walk, your feet push on the ground and the ground pushes back. The walls of a building or pillars of a bridge push upwards, and prevent the roof or bridge from falling down. These are called reactive forces. The air inside a balloon pushes on the rubber walls of the balloon, and the force causes the rubber to stretch.
24. What are Magnets Used For?
Magnets are used for lots of things. They can be used to keep the doors of cupboards closed. The needle of a compass is a magnet and always points to the North Pole. Electromagnets are used in doorbells and also in switches worked by electricity called relays. We also use them in motors, electric generators
for making electricity and MRI scanners for seeing inside our bodies
25. Are Magnets Really Strong?
Some magnets are very strong. Some of the strongest magnets are used in hospitals in MRI scanners. These magnets are so strong that they can pull metal items out of your clothes or body if they aren't removed beforehand.
26. What is an Electromagnet?
An electromagnet is a magnet worked by electricity. When electricity flows through a wire wrapped many times around a piece of iron, the iron becomes an electromagnet. You can make one by wrapping insulated wire a few hundred times around a nail and connecting it to a battery.
27. Why is Wire Used For Electricity Covered With Plastic?
Plastic is an electrical insulator. An insulator is a material that doesn't conduct electricity. This means that electricity can't pass through it. This keeps you safe from the electricity and also stops the electricity from flowing to where it's not supposed to go. Other materials that are insulators are ceramic (like the stuff in cups and plates), rubber and glass.
28. Why Can I See Through Glass?
The answer is really complicated and not even the best scientists are sure. However we know that really good glass transmits a lot of light, but reflects and absorbs very little.
29. What is Glass Used for Apart From Bottles and Windows?
Glass is used to make lenses. Lenses can bend light that passes through them so they're used in glasses to correct people's sight who can't see things clearly that are near to them or far away. Lenses are also used in telescopes and microscopes and lasers.
30. What Can I See With a Microscope?
You can see really small things such as bacteria. The most powerful microscopes are called electron microscopes and can see viruses. These viruses, such as COVID-19, are much smaller than bacteria and cannot be seen with an ordinary microscope that works on light.
31. How Big is a Bacteria?
Bacteria are really small and range from about 0.5 to 5 microns long. A micron is one thousandth of a mm. So it would take nearly one thousand bacteria placed end-to-end to measure one mm or 1/20 of an inch. Some bacteria are very big and can just about be seen with the naked eye, which means without a microscope or magnifying glass. These are about half a millimeter long. Bacteria are much bigger than atoms though. Many bacteria are useful and help breakdown organic matter in our environment like leaves from trees and the dead bodies of animals. Some of them even help to digest the food we eat. Others are harmful and make poisons or toxins that can make us sick.
32. What are Atoms?
Everything in the Universe is composed of atoms. They are sometimes described as the building blocks of matter and a bit like Lego because they join together to make bigger things. Everything we see around us is made from them. Atoms are made of even smaller pieces called protons, neutrons and electrons. In some materials, atoms join together to form molecules.