Scientists suppose there could be other life-bearing planets like Earth. To find them, they are looking for 'wobbling' stars. Physics - Universe - Learning Points. When a planet orbits a star, it has just enough gravitational force to...

The atmospheric composition of the sky affects the colours we see. From blue horizons to red sunsets, why do we see colours the way we do? Physics - Our Solar System - Learning Points. Light is made up of different wavelengths. Our...

Hot air balloons rely on heat alone to keep them in the sky. How does this work? Physics - Energy And Radioactivity - Learning Points. Hot air rises in cool air because it is less dense. The hot air within a hot air balloon creates the...

The air we breathe is made up of a mixture of gases. Discover the invisible forces of gas at work around us. Physics - Forces - Learning Points. The air we breathe is made up of gases including nitrogen, oxygen and carbon dioxide. The...

Find out why nitrogen is essential for life. Chemistry - Periodic Table - Learning Points. Nitrogen is found inside every organism on Earth. Nitrogen gas is very unreactive. Nitrogen gas is used as a food preservative. A Twig Context...

A look at the biological functions that produce burps and farts. Biology - Human Body - Learning Points. Burps are caused when swallowed air forces open the stomach sphincter and travels up the oesophagus. Farts are caused when swallowed...

Hydrogen is a highly flammable element, with the potential to become a non-polluting alternative to gasoline. Chemistry - Periodic Table - Learning Points. Hydrogen is the element with the lowest density. Hydrogen is highly flammable and...

Combustion reactions are vital: from keeping us warm and cooking our food, to providing electricity and propelling rockets into outer space. What do we know about these chemical reactions? Chemistry - Reactions - Learning Points....

In 1869, Russian scientist Dmitri Mendeleev created the Periodic Table, ordering the naturally occurring elements by their structure and properties. His Periodic Table changed the course of Chemistry forever, and even predicted the...

How a race between two scientists to liquefy gases led them near to absolute zero - the coldest temperature possible. Physics - Energy And Radioactivity - Learning Points. Absolute zero occurs at -273.15 degrees Celsius. Absolute zero is...

Find out how chromatography can be used to create the chemical 'colour fingerprint' of a substance. What are the two chromatography methods and how are they used to solve crimes? Chemistry - Atoms And Bonding - Learning Points....

Discover the role played by intermolecular forces in changing the state of matter between solid, liquid and gas. Chemistry - Atoms And Bonding - Learning Points. Intermolecular forces are the attractive forces between molecules....

The 17th century German chemist Johann Becher proposed that an element, phlogiston, was released when substances burned. He was wrong, and his incorrect theory led many early chemists to misunderstand the significance of some of their...

Lasers are usually associated with heat. But scientists have instead used them to reach the coldest temperature ever recorded. Could they reach absolute zero? Physics - Energy And Radioactivity - Learning Points. Absolute zero is...

What are stars made of? How are they born, how do they live, and how do they die? Physics - Our Solar System - Learning Points. Our nearest star is the Sun. A star is formed from a cloud of dust and gas, which shrinks under gravity and...

The discovery of Titan's atmosphere excited scientists, who believe it could hold the key to life on Earth. Physics - UniverseLearning Points. Titan is the only moon in the Solar System with a dense atmosphere. Titan's atmosphere is 98%...

Earth has always had changeable weather, but now the world's climate is getting warmer. What is global warming, why is it a problem and how can we stop it? Earth Science - Human Impacts - Learning Points. Most scientists agree that human...

Discover the damage caused by shockwaves and how they are created by supersonic speeds. Physics - Waves - Learning Points. Waves of high pressure are produced when something moves through a medium at supersonic speed. At supersonic...

Two or more atoms held strongly together by covalent bonds. A Twig Science Glossary Film. Key scientific terms defined in just 60 seconds using stunning images and concise textual definitions. Twig Science Glossary Films reinforce...

We lower a helium-filled balloon into liquid nitrogen to see how the change in temperature affects its volume. When it hits the cool liquid nitrogen, the gas inside contracts and the volume of the balloon decreases. When it is removed...

We release carbon dioxide from a fire extinguisher against a dark cloth to see what happens. The expanding gas cools as it leaves the extinguisher, forming a visible dry ice solid on the cloth. As it warms, the carbon dioxide vanishes...

Halogens are hazardous to human life, yet they can also be very useful. How do they react when they meet other elements? Chemistry - Periodic Table - Learning Points. The halogens are the elements in Group 7 of the periodic table. The...

How the orbit of the planets is dictated by mass and the force of gravity. Physics - Our Solar System - Learning Points. The curved path of one object around another is its orbit. Objects orbit due to the effects of gravity. The...

Knowing the rate of a chemical reaction can be very important, particularly for industry. Discover which factors indicate the rate of a chemical reaction, and how you can change it. Chemistry - Reactions - Learning Points. Some reactions...