Here's why:

* Photosphere: This is the visible surface of the sun. It's a relatively thin layer about 500 kilometers deep, where the sun's temperature is around 5,500 degrees Celsius (9,932 degrees Fahrenheit). At this temperature, hydrogen atoms are ionized, releasing photons of light, including those in the visible spectrum.

* Other layers:

* Core: The sun's core is where nuclear fusion occurs, generating energy that powers the sun. However, the core is completely obscured by the outer layers.

* Radiative zone: This layer transports energy outward through radiation. It's too dense for visible light to escape directly.

* Convective zone: This layer moves energy outward through convection currents. While hot gas rises and cools, it doesn't emit significant visible light.

* Chromosphere: This layer lies above the photosphere. It's much hotter than the photosphere, but it emits mostly ultraviolet light.

* Corona: The outermost layer of the sun's atmosphere is extremely hot and emits X-rays.

So, the photosphere is the only layer of the sun that emits the visible light we see.