Astronomical spectroscopy
![The Star-Spectroscope of the Lick Observatory in 1898. Designed by James Keeler and constructed by John Brashear.](/Images/godic/202412/22/Star-Spectroscope4326.jpg")
![Electromagnetic transmittance, or opacity, of the Earth's atmosphere](/Images/godic/202412/22/Atmospheric_electromagnetic_opacity.svg4326.png")
![Incident light reflects at the same angle (black lines), but a small portion of the light is refracted as coloured light (red and blue lines).](/Images/godic/202412/22/Blazedgrating4327.jpg")
![Black body curves for various temperatures.](/Images/godic/202412/22/Black_body.svg4327.png")
Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure the spectrum of electromagnetic radiation, including visible light and radio, which radiates from stars and other hot celestial objects. Spectroscopy can be used to derive many properties of distant stars and galaxies, such as their chemical composition, temperature, density, mass, distance, luminosity, and relative motion using Doppler shift measurements.