The part of the Sun that gives off light is its photosphere.

Here's why:

* The photosphere is the Sun's visible surface. It's the layer we see when we look at the Sun.

* It's a layer of hot gas (plasma) that emits light and heat. The intense heat and pressure within the Sun cause hydrogen atoms to fuse into helium, releasing tremendous amounts of energy in the form of light and heat.

* The photosphere is about 400 miles (640 km) thick. It's the lowest layer of the Sun's atmosphere.

While the Sun has other layers (like the chromosphere and corona), the photosphere is the layer responsible for the light we see.