Why Do We See Different Colours? The Science Behind Photons and Light

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Updated on: Educator Review By: Michelle Connolly

Have you ever wondered how the world explodes with colour every morning? The answer lies in tiny, invisible travellers called photons. These little packets of light energy might seem small, but they’re the reason you can see everything. 

What are these mysterious photons, and where do they come from? How do they travel at incredible speeds across space, and why do they give us the dazzling colours we see?

Get ready to understand the incredible world of photons and light! Let’s discover where these tiny travellers come from, how they race across space, and how they paint our world with colours beyond imagination. 

What Are Photons?

Photons are elementary particles, meaning they have no internal structure and are among the most basic building blocks of the universe. Each photon carries a particular amount of energy, which determines its colour and behaviour.

A photon is like a single raindrop. Just as raindrops come in different sizes, carrying different amounts of water, photons come in different “sizes” based on their energy. Larger, more energetic photons have shorter wavelengths and appear blue or violet, while smaller, less energetic photons have longer wavelengths and appear red or orange.

Where Do Photons Come From?

Ever wondered where all the light in our world comes from? The answer lies in the creation of photons. So, where do these light-bringers begin their journey?

The Sun

Our closest star, the Sun, is the biggest producer of photons in our solar system. Inside the Sun, atoms bump into each other at incredible speeds, releasing huge amounts of energy. This energy gets converted into photons, which then zoom out in all directions, reaching us in about eight minutes as sunlight, bringing warmth, light, and life to Earth.


On a warm summer night, tiny specks of light dance in the darkness called fireflies! These little creatures have a special ability to create their own light through a chemical reaction. Inside their bodies, a substance called luciferin reacts with oxygen, releasing energy in the form of photons, making them glow like miniature lanterns.

Even though their light is much fainter than the Sun’s, fireflies show us another way photons can be born.

Light Bulbs

Electricity flows through a thin wire inside the bulb, making it heat up. This heat causes the atoms in the wire to vibrate very quickly, releasing energy as photons. Depending on the type of bulb, these photons create different colours of light, illuminating our homes and streets.

Different types of bulbs use different methods to create photons, but they all rely on converting other forms of energy into light energy.

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Other Photon Sources

Our world is filled with even more sources of photons! Lightning strikes release bursts of light energy, while stars shine brightly due to nuclear reactions within them. Even everyday things like phone screens and glow-in-the-dark toys emit photons in different ways.

How do Photons Travel?

So, we know where photons come from, but how do these tiny light packets get from their source to reach our eyes? Let’s explore the incredible path of photons.

The Fastest in the Universe

Photons are the fastest things in the universe, zooming at a whopping almost 300,000 kilometres per second! That’s so fast; they could travel around the Earth seven times in just one second! This incredible speed allows them to reach us from the Sun in just eight minutes and from stars millions of light-years away.

Why are they so speedy? Photons have no weight. This means they don’t need to push against anything to move, allowing them to travel at the ultimate speed limit set by the universe.

Travelling Through Different Paths

While photons are super speedy, their path can change depending on where they travel. In empty space, like between stars, they zoom along in a straight line. When they enter different materials, like air or water, things get interesting.

Let’s think of light bouncing off a mirror. Photons hit the mirror’s surface and “bounce” back like tiny balls, changing their direction. This is called reflection, and it’s why we can see ourselves in mirrors.

Water and glass can also bend the path of photons. This bending is called refraction, and it’s why objects look distorted underwater or through a magnifying glass.

Different Speeds in Different Materials

Photons can travel through different materials like air, water, and even glass. However, their speed and direction can change depending on the material. They slow down slightly when they pass through something like water or glass compared to empty space. 

This difference in speed is what causes refraction, bending the light’s path. This is why a swimming pool looks shallower than it actually is, as the light bends as it passes through the water.

A Wave-Particle Duality

Even though they’re tiny packets, photons can bend around corners and even “bump” into each other like water waves. This might seem strange, but it’s a special secret of light and tiny things in the universe.

It’s important to remember that photons are neither purely particles nor purely waves. They exhibit both characteristics depending on the situation.

How Photons Create Different Colours of Light

We’ve learned that photons are tiny packets of light energy, but how do they create the vast array of colours we see in the world? The secret lies in a fun fact: not all photons are created equal!

Wavelengths and Energy

Each photon has a specific amount of energy directly related to its wavelength. The wavelength is like the distance between two peaks of a wave on water. Shorter wavelengths have higher energy, while longer wavelengths have lower energy.

When sunlight shines through a prism, it bends different wavelengths differently, separating them into the beautiful colours of a rainbow. Red light has the longest wavelength and lowest energy, while violet light has the shortest wavelength and highest energy.

This explains why different objects appear in different colours. An object reflects only certain wavelengths of light while absorbing the rest. A red apple, for example, reflects mostly red light and absorbs other colours, making it appear red to our eyes.

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How Our Eyes See Colour

Our eyes are amazing tools for capturing and interpreting light. Inside our eyes, there are special cells called cones that are designed to detect different wavelengths of light. There are three main types of cones; each one is sensitive to a specific range of wavelengths (red, green, and blue).

As light enters our eyes, it stimulates these cones depending on its wavelength. Our brain then interprets these signals to produce the sensation of colour. This means the colour we see isn’t actually a property of the object itself but how our brain interprets the light reflected from it.

The Amazing Uses of Photons and Light

Photons aren’t just for creating beautiful colours and helping us see. These tiny light travellers play a vital role in many aspects of our everyday lives and hold exciting possibilities for the future! Let’s explore some amazing uses of photons.

Seeing the World Around Us

The most obvious use of photons is enabling us to see. Our eyes rely on different wavelengths of photons to perceive the vast spectrum of colours. 

From the traditional light bulbs in our homes to the powerful beams in hospitals, photons help us see and navigate the world around us. Different types of lights, like LEDs and lasers, use different ways to create photons, offering various benefits like energy efficiency and precise control.

Communication and Information

Lasers transmit information through light pulses, carrying data across vast distances at incredible speeds. This technology powers the internet, phone calls, and even TV broadcasts, connecting us and sharing information globally.

Beyond communication, photons also play a role in storing information. CDs, DVDs, and even some newer memory devices like Blu-ray discs use lasers to read and write data encoded in the form of tiny dots on their surfaces. These dots reflect or absorb light differently, storing and retrieving information for future use.

Energy and Sustainability

Solar panels harness the sunlight energy by converting photons into electricity, powering homes, businesses, and even entire cities. This clean and sustainable way of using light energy helps reduce our dependency on fossil fuels and combat climate change

Beyond solar power, lasers are becoming increasingly important in other renewable energy sources like nuclear fusion. By precisely manipulating photons, scientists hope to unlock the immense potential of this clean and abundant energy source, shaping a sustainable future.

Beyond Everyday Uses

The world of photons extends beyond everyday applications. In medicine, lasers are used for precise surgeries and treatments, while medical imaging techniques like X-rays and MRI scans use different types of light waves to diagnose and understand diseases.

Space exploration relies heavily on light. Telescopes gather faint photons from distant stars and galaxies, revealing the secrets of the universe. Even spacecraft communication with Earth uses lasers for fast and reliable data transmission.

Ultimately, photons and light interact with the world, carrying energy and information and even shaping life as we know it. If you enjoyed this exploration, check out more useful resources on LearningMole; learn what electricity is or discover some interesting facts about electromagnetic waves.

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