Every morning, the Sun comes up and lights up the whole sky. It looks like a bright round circle, roughly the size of a coin if you hold one up at arm's length. But here's something that will blow your mind: that little circle in the sky is so enormous that more than one million planet Earths could fit inside it. That's not a typo. One. Million. Earths.
The Sun only looks small because it is very, very far away. Think about this: if you saw a cricket ball on the other side of a giant field, it would look like a tiny dot. But walk up to it and it's actually quite big. The Sun is like that, except instead of a field between you and it, there is 150 million kilometres of empty space. That's so far that even light, the fastest thing in the universe, takes about eight minutes to travel from the Sun all the way to your eyes. So when you look at the Sun in the morning, you're actually seeing what it looked like eight minutes ago!
Here's an easy way to picture how big the Sun really is. Imagine the Sun is a basketball. If that's the Sun, then Earth would be a tiny mustard seed sitting all the way across a football field. That's how different their sizes are. The Sun is so wide that if you lined up 109 Earths side by side, they would just about stretch across it. And it is so heavy that it makes up more than 99 percent of everything in our entire solar system, including all eight planets, all the moons, all the asteroids, and all the comets put together.
Indian astronaut Kalpana Chawla once said, "When you look at the stars and the galaxy, you feel that you are not just from any particular piece of land, but from the solar system." And the Sun is the heart of that solar system. Its gravity is so strong that it holds everything in place, keeping all the planets, including Earth, moving in their orbits instead of flying off into deep space.
The Sun is not just big. It is also incredibly hot. The surface of the Sun is about 5,500 degrees Celsius, which is hot enough to melt any metal you can think of, thousands of times over. But the very centre of the Sun, called the core, is even hotter: about 15 million degrees Celsius. That's where the real action happens. The Sun squashes hydrogen atoms so tightly together that they join up and become helium, and that process releases a huge burst of energy. That energy is what eventually becomes the sunlight that warms your face and helps plants grow.
Even though the Sun seems incredibly special to us, it is actually a fairly ordinary star. Scientists have found stars out there that are a hundred times bigger than the Sun. Our Sun just happens to be the star closest to us, which is why it looks so big and bright compared to the tiny twinkling dots of other stars in the night sky.
So the next time you feel the warmth of the Sun on your skin, remember that you are feeling energy that was created at the heart of a star a million times bigger than Earth, travelling 150 million kilometres through space, just to reach you. Not bad for something that looks like it could fit behind a coin.