March 6th is Joseph von Fraunhofer's birthday. Fraunhofer was a German physicist who discovered thin dark bands while investigating the sun's spectrum. Bunsen and Kirchhoff later discovered that they corresponded to the wavelengths of the absorption of common elements like hydrogen, helium and iron. The energy from the sun would pass through the upper layers of the sun and get absorbed, causing the dark lines. These lines are now known as "Fraunhofer lines" in his honor.