How old is sunlight?

We all learn that light from the Sun takes around 8 minutes and 20 seconds to reach Earth. And that’s true—for light traveling through space from the surface of the Sun to us.

But here’s the twist:

That light actually began its journey inside the Sun about 170,000 years ago. 😮

Here’s what happens:

Photons are created in the Sun’s core during nuclear fusion. But the inside of the Sun is so dense that photons don’t just shoot straight out. They bounce around—absorbed and re-emitted—countless times in a chaotic journey known as radiative diffusion. It's like a maze that takes thousands of years to escape.

Only once a photon reaches the Sun’s surface can it finally stream freely through space—and just 8 minutes later, it hits your face.

☀️ But wait—there’s more:

Light is the fastest thing in the universe, and according to Einstein’s relativity, the faster you move through space, the slower you move through time. Since light moves at the speed of light, from its own perspective, no time passes at all.

So even though that sunlight took 170,000 years to reach you...

🔹 For the light itself, it was instantaneous.

Subscribe to CuriosityQuest to Level-Up your Scientific Knowledge! Satisfy your curiosity and learn about topics like Black Holes, Quantum Entanglement, and life on Earth and beyond.

Get your free eBook now by subscribing!