Figure 9-9 Spicules in the Chromosphere This schematic diagram shows the three layers of the solar atmosphere. The lowest, the photosphere, is about 250 miles thick. The chromosphere extends about 1250 miles higher, with spicules jutting up to about 6,000 miles above the photosphere. Above a transition region is the Sun’s outermost layer, the corona. It extends many millions of miles out into space.