Аннотация:The aim of this paper is to attract attention of astronomers which observe stars, and first of all the Sun as a star, with a high spectral resolution to the possibility of using their observational results, containing telluric lines, to study global changes of the composition and other properties of the Earth's atmosphere. We demonstrate this possibility on the example of solar spectral observations in Moscow in visible and near-infrared ranges. By comparison of equivalent widths of the lines of O2 (lambda629 angstrom) and CO2 (lambda20700 angstrom) recorded by a spectrograph on the large vertical solar telescope ATB-1 of the P. K. Sternberg Astronomical Institute of Moscow State University in 1969 and 1991-1993, the conclusion has been drawn that, during the last 22-24 years, the O2 content in the Earth's atmosphere has not changed within the accuracy of observations. During the same time, the carbon dioxide content significantly increased.