Answer:
The energy generated and stored in the core diffuses (spreads) outward by radiation (mostly gamma-rays and x-rays) into the next layer, the photosphere——the most visible surface of the Sun——and beyond. Here, gaseous layers change from being completely opaque (blocking light) to a radiative (particle/wave energy) condition to being transparent (admitting light). In the chromosphere, the rising heat causes hydrogen to give off the reddish light seen in the prominences during solar eclipses.
Extra Details That might help:
the chromosphere is the innermost atmospheric layer. It is just above the photosphere. Here the temperature begins to rise again, to about 36,000 degrees F. Above the chromosphere is the transistion layer, where temperatures increase 6000 to over half-a-million degrees. Gases in this layer shine in the ultraviolet and extreme ultraviolet wavelengths. The outermost atmospheric layer is the corona, which gets really hot, almost 2,000,000 degrees F. This is where the solar wind begins. These layers can only be seen during total solar eclipses. Here is where we see towering masses of luminous gas, called filaments or prominences, on the solar limb against the dark sky.