Through the use of diffraction gratings, the spectral content of light from outer space that reaches the Earth can be examined. This allows astronomers to determine amazing facts about the universe around us including the composition of stars and the movement of galaxies. Through these discoveries, we now know the age of the universe and know that it’s expanding. Spectroscopic analysis of distant objects is difficult due to the low intensity of the light that reaches our ground- or space-based telescopes. Selecting a grating of high efficiency and of sufficient size for the telescope is critical to success. The gratings below are suitable for use in astronomical instrumentation.