
thumb|The solar disk observed in four different wavelengths of ultraviolet radiation by the Atmospheric Imaging Assembly spectroheliograph on board the [[Solar Dynamics Observatory. From left to right, the wavelengths imaged are 171, 304, 335, and 94 Å. Colors are false and added in postprocessing.]] The spectroheliograph is an instrument used in astronomy which captures a photographic image of the Sun at a single wavelength of light, a monochromatic image. The wavelength is usually chosen to coincide with a spectral wavelength of one of the chemical elements present in the Sun.
thumb|The solar disk observed in four different wavelengths of ultraviolet radiation by the Atmospheric Imaging Assembly spectroheliograph on board the [[Solar Dynamics Observatory. From left to right, the wavelengths imaged are 171, 304, 335, and 94 Å. Colors are false and added in postprocessing.]] The spectroheliograph is an instrument used in astronomy which captures a photographic image of the Sun at a single wavelength of light, a monochromatic image. The wavelength is usually chosen to coincide with a spectral wavelength of one of the chemical elements present in the Sun.
It was developed independently by George Ellery Hale and Henri-Alexandre Deslandres in the 1890s and further refined in 1932 by Robert R. McMath to take motion pictures.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).