Periodic gravity waves have been observed over São João do Cariri (7.4 degrees S; 36.5 degrees W) in the lower thermosphere from September 2000 to November 2010 using OI 630 nm airglow images. This video shows an example of the periodic waves observed on 20 September 2006. On the left side, one can see the raw airglow images, while, on the right panel, one can see the processed images using a high pass Butterworth filter and they were corrected to the geographic coordinates. The gravity wave is propagating southwestward, it looks like waves on the water surface from the left images. Note that the Milk Way can be observed in the both sequence of images almost parallel to the gravity waves phase fronts. The small white circles on the left images represents either stars or planets.