What is the visible surface of the Sun called?

The visible surface of the Sun is called the photosphere. This layer is where the Sun’s light is emitted, making it the part that we typically see when looking at the Sun. The photosphere has a temperature of about 5,500 degrees Celsius and is made up of a dense layer of gas that has a somewhat grainy appearance due to convective processes, where hot plasma rises and cooler plasma sinks.

The corona is the outermost layer of the Sun's atmosphere, visible during a solar eclipse, and is much hotter than the photosphere, while the chromosphere lies just above the photosphere and can sometimes be seen during solar eclipses as a red rim. Prominences are large, bright features that extend outward from the Sun's surface, often in loop shapes, whereas sunspots are cooler, darker areas found on the photosphere itself. Understanding these layers helps to appreciate the structure and behavior of the Sun as a star.