All About the Sun: The Star at the Center of Our Solar System

Did you know that the Sun is actually a star? It's not just any star—it's a massive ball of plasma that gives us light and heat. Without it life on Earth wouldn't be much fun at all. Read on to learn more about the superstar at the centre of our Solar System.

What is the Sun Made Of?

The Sun is primarily composed of plasma. Here's a quick science lesson: If you heat up a solid, it becomes a liquid; heat a liquid, and it turns into a gas; heat a gas, and you get plasma. This means the Sun is essentially a hot ball of plasma.

Physical States of Matter. Credit: Britannica

Why is the Sun Important?

The Sun is crucial for life on Earth. Here are a few reasons why:

1. Light and Heat: The Sun provides the light and heat necessary for life. Without it, our planet would be dark and cold, making it impossible for plants to perform photosynthesis, which is the process they use to create food and oxygen. This, in turn, supports all life forms on Earth.

2. Weather and Climate: The Sun's energy drives the Earth's weather systems and climate. It causes the evaporation of water, forming clouds and precipitation, and contributes to wind patterns. The Sun’s energy balance helps maintain the Earth's climate and supports various ecosystems.

3. Seasons: The tilt of the Earth's axis and its orbit around the Sun result in the changing seasons. This variation in sunlight throughout the year affects agriculture, wildlife behaviour, and human activities.

4. Solar Energy: The Sun is a massive source of renewable energy. Solar panels convert sunlight directly into electricity, providing a clean and sustainable energy source.

Without the Sun, the Earth would be a lifeless, frozen rock. Its energy is the driving force behind everything from our weather systems to the food we eat.

the Sun Data Dump

Diameter: The Sun's diameter is about 1,392,000 kilometers (864,000 miles).

Temperature: The Sun's surface temperature is around 5,500 degrees Celsius (9,940 degrees Fahrenheit).

Rotation: The Sun rotates on its axis once every 25 days.

Composition: The Sun is made up of 70% hydrogen, 28% helium, and 2% other elements.

Distance from Earth: The Sun is 149,600,000 kilometres (92,900,000 miles) away from Earth. It's important never to look directly at the Sun because it can damage your eyes.

The Sun Compared to Other Stars

The Sun is a yellow dwarf star, which means it's relatively small compared to other stars. For instance, UY Scuti is 1,700 times larger than the Sun!

Credit: NASA/Penn State University

Credit: The Secrets of the Universe

What Colour is the Sun?

Contrary to popular belief, the Sun is actually white, not yellow, orange, or red. It emits all colors of visible light, which blend together to create white light. The reason we often see it as yellow or orange from Earth is due to our atmosphere scattering shorter blue and violet wavelengths, leaving behind the warmer tones. If viewed from space, without atmospheric interference, the Sun would appear pure white.

NASA's Mission to the Sun

Credit: NASA/Johns Hopkins APL/Steve Gribben

In 2018, NASA launched the Parker Solar Probe with the ambitious goal of studying the Sun up close. This mission is groundbreaking for several reasons:

1. Getting Closer to the Sun: The Parker Solar Probe is designed to swoop within about 6.5 million kilometres (4 million miles) of the Sun's surface. This is significantly closer than any previous spacecraft has ever ventured.

2. Understanding the Corona: The Sun’s outer atmosphere, known as the corona, is much hotter than its surface. The Parker Solar Probe aims to understand why this is the case. By studying the corona, scientists hope to gain insights into the fundamental physics of stars.

3. Solar Wind: The Sun emits a stream of charged particles known as the solar wind, which affects the entire solar system, including Earth. Understanding the solar wind's acceleration and dynamics is one of the probe's primary objectives.

4. Energy Flow: The probe will trace the flow of energy from the Sun's core to its outer atmosphere. This includes studying how magnetic fields and energetic particles interact within the solar atmosphere.

According to NASA, In 2021, the Parker Solar Probe made history by becoming the first spacecraft to enter the Sun's corona, providing unprecedented data on its composition and behaviour. Since then, the mission has continued to revolutionise our understanding of the Sun and its influence on the solar system. Notably, on 24 December 2024, the probe achieved its closest approach yet, coming within 6.1 million kilometres (3.8 million miles) of the solar surface and travelling at a record-breaking speed of 692,000 kilometres per hour (430,000 miles per hour). These milestones have offered invaluable insights into solar phenomena, enhancing our comprehension of the Sun's dynamics.

Layers of the Sun

Credit: NASA/Goddard

1. Core: The core is the hottest part of the Sun, with temperatures reaching 15 million degrees Celsius (27 million degrees Fahrenheit). Here, nuclear fusion occurs, where hydrogen atoms fuse to form helium, releasing immense energy. This energy powers the Sun and produces the light and heat we receive on Earth.

2. Radiative Zone: Surrounding the core, the radiative zone extends up to 70% of the Sun's radius. In this zone, energy is transferred outward by radiation. Photons, or particles of light, bounce around in this zone for thousands to millions of years before reaching the outer layers.

3. Convective Zone: Above the radiative zone is the convective zone, where temperatures drop to around 2 million degrees Celsius. In this layer, energy is transported by convection currents. Hot plasma rises to the surface, cools down, and then sinks back down to be reheated, much like the motion in a lava lamp.

4. Photosphere: This is the visible surface of the Sun that we see from Earth. The photosphere has a temperature of about 5,500 degrees Celsius and is the layer that emits the light we see.

5. Chromosphere: Above the photosphere lies the chromosphere, which is about 4,000 to 10,000 degrees Celsius. This layer is where solar flares and other eruptions occur, and it's characterised by a reddish glow visible during solar eclipses.

6. Corona: The corona is the Sun's outermost layer, extending millions of kilometres into space. Despite being the farthest layer from the core, the corona is the hottest, with temperatures ranging from 500,000 to 1 million degrees Celsius. It's visible as a glowing halo during a total solar eclipse.

During a solar eclipse, we can see the corona, which appears as a beautiful halo around the Sun.

Credit: NASA/Aubrey Gemignani

Fun Sun Facts

The Sun is the ultimate heavyweight champion of our solar system, making up a staggering 99.86% of its total mass. That means if you took everything else—all the planets, moons, asteroids, comets, and even Pluto (yes, Pluto too)—and squashed them together, they’d still be just a tiny fraction of the Sun’s bulk. In other words, if the solar system were a giant cosmic pie, the Sun would be almost the whole thing, leaving just a few crumbs for everything else!

The Sun is so massive that you could stuff about 1.3 million Earths inside it.

To put that into perspective, if the Sun were a giant gumball machine, Earth would be just one tiny gumball among over a million others. 

In our video, we created a model of the Sun using different colours of play dough to represent its layers. It was a fun look at the Sun's structure.

Check it out here

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