As early as 1885, Noctilucent Clouds (NLC) have been recorded and studied due to their enigmatic properties, however they did not gain serious attention until just in the last couple of decades. Research on data collected from the 1960’s on have indicated that the frequency of occurrence and the brightness of NLC may be increasing, and as such may be an indicator of changes occurring in our atmosphere. When viewed from space, NLC are called Polar Mesospheric Clouds (PMC). Since the beginning of the 1970’s, instruments on satellites that were designed for other purposes have observed PMC and have been used to extrapolate their physical properties, such as POAM, WIND, SME, and SBUV. Currently the importance of monitoring PMC has grown to the level that dedicated satellites and ground stations watch for trends in PMC occurrence, in the hopes that they might reveal changes in the global environment. PMC formation is directly dependant on the cold summer mesosphere caused by complex planetary circulation patterns and water vapor propagated vertically through the stratosphere into the mesosphere. Brightness and occurrence frequency of PMC have been shown to follow planetary wave activity, gravity waves, and the solar cycle.