Polar mesospheric clouds (PMCs) form at very high altitude (around 80 km) over high latitudes in the Northern and Southern Hemispheres. Because of their altitude, seasonality, and tenuous nature, PMCs are not well understood. This letter presents a method for detecting PMCs using geostationary satellite images of the Earth's limb. The method is tested against data from the Aeronomy of Ice in the Mesosphere mission that was specifically designed for PMC detection. It is found that the new method is successful in detecting seasonal trends in PMC formation and, due to the larger data set of geostationary images, may allow examination of the temporal properties of PMCs in greater detail than possible by satellites in polar orbit.