06 Solar image on a widely opened spectroscope slit

This image, taken from Professor Charles A. Young's book, "The Sun," shows conceptually how an image of the Sun can be placed tangentally to a widely opened spectroscopic slit. In this case, the bright solar photosphere will not enter the spectroscope. However, much fainter chromospheric structure, if present, will fall into the slit. If the spectroscope is tuned to a naturally wide solar absorption line, such as hydrogren alpha, chromospheric structure, glowing in emission, can be imaged through the spectroscope. This concept is closely related to how a spectroheliograph works.