Atmosphere of Earth development of animals. Today's atmosphere contains 21% oxygen, which is great enough for this rapid development of animals. "Air pollution" is the introduction into the atmosphere of chemicals, particulate matter or biological materials that cause harm or discomfort to organisms. Stratospheric ozone depletion is caused by air pollution, chiefly from chlorofluorocarbons and other ozone-depleting substances. The scientific consensus is that the anthropogenic greenhouse gases currently accumulating in the atmosphere are the main cause of global warming. On October 19, 2015 NASA started a website containing daily images of the full sunlit side of Earth on http://epic.gsfc.nasa.gov/. The images are taken
Upper Atmosphere Research Satellite simultaneously. SUSIM measured ultraviolet (UV) emissions from the sun. The observations are made both through vacuum and through occultations of the sun through the atmosphere. This allowed a comparison of the amount of UV light that reaches the earth and the amount absorbed by the upper atmosphere. Because of the energy of UV, instrument degradation is a major issue. To help with this problem, the instrument contained two identical spectrometers. One was used almost continuously during the daylight portion of UARS’ orbit. The second was used infrequently to verify the sensitivity of the first. The Solar Stellar Irradiance Comparison Experiment