Earth ozone layer due to the subsequent conversion of atmospheric into. The ozone layer blocks ultraviolet solar radiation, permitting life on land. Other atmospheric functions important to life include transporting water vapor, providing useful gases, causing small meteors to burn up before they strike the surface, and moderating temperature. This last phenomenon is known as the greenhouse effect: trace molecules within the atmosphere serve to capture thermal energy emitted from the ground, thereby raising the average temperature. Water vapor, carbon dioxide, methane, nitrous oxide, and ozone are the primary greenhouse gases in the atmosphere. Without this heat-retention effect, the average surface
Life on Titan of life in the universe. In the 1970s, astronomers found unexpectedly high levels of infrared emissions from Titan. One possible explanation for this was the surface was warmer than expected, due to a greenhouse effect. Some estimates of the surface temperature even approached temperatures in the cooler regions of Earth. There was, however, another possible explanation for the infrared emissions: Titan's surface was very cold, but the upper atmosphere was heated due to absorption of ultraviolet light by molecules such as ethane, ethylene and acetylene. In September 1979, Pioneer 11, the first space probe to conduct fly-by observations of Saturn