Astronomical spectrograph
Disperses light to reveal composition, temperature and velocity.
Overview
By dispersing starlight into spectra, 19th-century spectrographs revealed chemical composition, temperature and radial motion of celestial bodies. Spectroscopy turned astronomy into astrophysics and remains the backbone of virtually every observational program.
Key discoveries
- Identification of stellar chemical composition
- Discovery of helium in the solar spectrum (1868)
- Measurement of stellar radial velocities