Fraunhofer lines
![Solar spectrum with Fraunhofer lines as it appears visually.](/Images/godic/202501/14/Fraunhofer_lines.svg0730.png")
![Spectrum of blue sky. Dips are present at the Fraunhofer line wavelengths.](/Images/godic/202501/14/Spectrum_of_blue_sky.svg0730.png")
![A demonstration of the 589 nm D2 (left) and 590 nm D1 (right) emission sodium D lines using a wick with salt water in a flame](/Images/godic/202501/14/Cmglee_Cambridge_Science_Festival_2016_sodium_lines0730.jpg")
In physics and optics, the Fraunhofer lines are a set of spectral lines named after the German physicist Joseph von Fraunhofer (1787–1826). The lines were originally observed as dark features (absorption lines) in the optical spectrum of the Sun.