The spectroscopy is a powerful tool that has allowed a better understanding of the properties of celestial objects and their changes over time; this can be exploited to study the influence of the Earth's atmosphere on the Sun radiation, during the day, and on the light reflected by the moon in the night. This provides radiation sources, relatively stable and well-known, allowing to track some atmospheric processes that produce spectral variation by absorption as well as by scattering. In this paper, the spectral changes of the Sun and Moon light, attributable to air pollution in the lower atmosphere on Cali city during several months in the years 2006 and 2007, are reported. A 10-inch Newtonian telescope was used. A light collector was build to study the lunar light; and for the sunlight, an optical reduction system was attached to a small telescope. These systems couple the colleted light into an optical fiber patch to feed the light into a spectrophotometer (350 nm to 1200 nm, with a resolution of 0.5 nm). The spectral signal was electronically processed and stored on a computer, and processed using the program ORIGIN 7.0 ® .