The Sun 3

The next layer of the Sun is called the photosphere. This is the visible surface of the Sun, which is composed of hot gases that act like a cloud surrounding the inner core and convection zone. The photosphere has a diameter of approximately 864,000 miles, which is approximately 109 times larger than then Earth. The photosphere is the region where hot gases rise and cooler gases descend back toward the Sun's center. These regions are known as granules, which are approximately 620 miles across. These granules give the photosphere a rough surface (Figure 5-10). The average temperature of the photosphere is approximately 9700 Fahrenheit.

Science of Earth Systems
By Stephen D. Butz
Chapter 5, The Life of Stars
Page 81