Figure 9-3 Solar Granulation (a) High-resolution photographs of the Sun’s surface reveal a blotchy pattern, called granulation. Granules, which measure about 1000 km (620 mi) across, are convection cells in the Sun’s photosphere. Inset: Gas rising upward produces the bright granules. Cooler gas sinks downward along the darker, cooler boundaries between granules. This convective motion transports energy from the Sun’s interior outward to the solar atmosphere. (b) At lower resolution, the Sun’s surface appears relatively smooth (the dark regions will be discussed shortly). Inset: Viewed near the Sun’s limb, granules are seen to bulge upward at their centers as a result of the convection that creates them.