Meet the Sun
Stop 2 of 12 · Inner Solar System
Meet the Sun
The Sun is a star — the glowing heart of the Solar System that holds everything in place.
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Understand that the Sun is a star, why it shines, and how its gravity keeps the planets in orbit.
Leela wakes early — earlier than the birds. Through her window, the sky is turning pink and gold. A huge, warm glow peeks over the horizon.
"Is the Sun a star?" she asks, remembering last night's conversation.
Manjari ruffles her feathers. "Aha — the same question, in daylight!"
Is the Sun really a star? It looks so different from the tiny lights at night.
Think about distance, Leela. If a big, bright lamp were far, far away, would it still look big and bright?
The Sun is a star — the very same kind of object as the tiny twinkling lights you see at night. It only looks big and bright because it is the closest star to us. Every star in the night sky is a sun of its own, just very, very far away.
Why Does the Sun Shine?
Deep inside the Sun, enormous pressure squeezes hydrogen gas together. This nuclear fusion releases an incredible amount of energy — the light and heat that reach us on Earth.
The Sun has been shining like this for about 4.6 billion years, and it will keep shining for billions more.
The Gravity That Holds Everything
The Sun is also the most massive object in the Solar System — it contains about 99.8% of all the mass in the whole system. That enormous mass creates strong gravity, which gently pulls the planets toward it.
So why don't the planets fall into the Sun? Because they are also moving sideways, very fast. Gravity pulls them in; sideways motion carries them forward. Together, these two effects keep each planet looping around the Sun in a stable orbit.
Drop a marble into a spinning bowl and watch it roll around the rim. It keeps circling the center — not falling in, not flying out. That is a little like how planets orbit the Sun!
The Scale of It All
About 1.3 million Earths could fit inside the Sun. It is hard to imagine — and that is exactly the point. The Sun is a star, and stars are enormous.
A yellow dwarf star
About 150 million km (93 million miles)
About 5,500 °C (9,900 °F)
About 4.6 billion years
How would life on Earth be different if the Sun did not exist?
Quick Check
Why do the planets stay in orbit around the Sun instead of drifting away?
The Sun is our nearest star. Its gravity keeps the whole Solar System together, and its light makes life on Earth possible.
Reflect
What You Discovered
- The Sun is a star — our nearest one
- The Sun's gravity holds the planets in orbit
- Its light and heat make life on Earth possible
- About 1.3 million Earths could fit inside