Final answer:
Absorption lines in the solar spectrum, called Fraunhofer lines, originate in the solar atmosphere, particularly from the cooler, external photosphere layer, where various elements absorb specific wavelengths of light coming from the Sun's interior.
Step-by-step explanation:
Absorption lines in the solar spectrum arise from the solar atmosphere, where atoms absorb sunlight at certain wavelengths. These lines, known as Fraunhofer lines, occur in the photosphere of the Sun, the layer just beneath the chromosphere and above the interior layers. The Sun's atmosphere is cooler than its hot interior, and when light from the interior passes through, certain wavelengths are absorbed by the cooler gas, creating dark lines in the spectrum.
The photosphere is the region of the solar atmosphere that we see as the visible surface of the Sun. Here, the light emitted from the lower layers travels through and interacts with the cooler gas, which includes various elements. The interaction leads to absorption at specific wavelengths, characteristic of each element, informing us about the Sun's composition.
The chromosphere lies above the photosphere and is responsible for the emission lines seen in the solar spectrum. These lines, which usually appear bright, are caused by the higher temperature and density in regions known as plages, which surround sunspots. The chromosphere contains the same elements found elsewhere in the Sun, but the spectral lines of hydrogen and calcium are especially noticeable because of their brightness.