A graphic with a black background and white text across the top that reads "How a Spectroscope Works." A Hubble image of a star cluster is seen near the top, white a white circle labeled as a Target Object. Yellow arrows and a beam point down the image, with just the beam continuing downward through a gray bar. That beam hits a diagonal gray line representing the grating. A rainbow beam of light then extends from the grating, aimed diagonally upward to the right and into a detector, which is also seen in rainbow hues.

hubble-spectroscopy-spectroscope-aug2023

When light from a celestial object enters the telescope, it passes through a tiny slit in a metal plate to isolate it from other light. The light then bounces off a special grating – a metal surface of tiny patterns - that splits the light into its constituent wavelengths. The split wavelengths are focused to hit a detector, which records them as a spectrum.

Credits: NASA Goddard/Shireen Dooling