Astronomers cannot look through Hubble’s lens to see the universe, as they can
with some ground-based telescopes. Instead, Hubble’s scientific instruments are
the astronomers’ electronic eyes. The telescope’s instruments include cameras
and spectrographs. The cameras don’t use photographic film, but rather electronic
detectors similar to those used in home video cameras. The spectrographs
analyze data by separating starlight into its rainbow of colors, just as a prism does to
sunlight. By closely studying the colors of light from a star, astronomers can decode
the star’s temperature, motion, composition, and age.