APOD 4.4 (Rio Morning Moonset)

Here, we see how quickly the moon moves across the sky, how quickly the light reflection off of it changes as its light passes through the low-hanging dust clouds in the atmosphere, and how quickly the city of Rio springs back to life each morning (since all the birds in the photo were only captured in the last frame).  When the moon is almost directly overhead, its reflected light doesn't pass through much dust between the Moon and your eyes, giving you the full spectrum.  However, as the moon approaches the horizon, it passes through a lot of dust before it reaches you.  The dust absorbs the darker colors, only letting a small amount of the redder light through.  By the time the moon actually sets, there is so much dust blocking the light that the moon becomes almost invisible.