The photosphere, shown as an orange vertical line, is the region where sunspots are formed. The less dense and turbulent chromosphere is a rapidly-changing filamentary structure that is seen during eclipses as a bright red ring around the Sun. The intensely active transition region, illustrated by the vertical yellow line, was first observed in detail by Skylab in the late 1970s. Spicules extend the chromosphere into the corona as pointed waves. Prominences and the corona reach far into interplanetary space.