What is the Sun's visible surface called?

What is the Sun’s visible surface called? The Sun’s visible surface is called the photosphere.

The photosphere is the layer from which most of the sunlight we see escapes. The Sun has no solid surface like Earth; it is a ball of plasma whose density changes gradually with depth. We call the photosphere the visible surface because it becomes opaque to visible light below this layer, while light can travel outward from its upper regions.

The word comes from Greek roots meaning “light” and “sphere.” The photosphere is roughly hundreds of kilometres thick and has an effective temperature of about 5,772 kelvin. Its surface shows granulation, a constantly changing pattern caused by hot plasma rising and cooler plasma sinking in convection cells. Sunspots are darker, cooler magnetic regions within it.

The photosphere is often confused with the chromosphere or corona. The chromosphere lies above it and can appear as a colored rim during a total solar eclipse; the much hotter corona forms the outer atmosphere. The heliosphere is larger still: it is the bubble created by the solar wind throughout interstellar space.