Good morning, Rallypoint. Today's Astronomy Picture of the Day (APOD) is titled "Omega Sunrise." Why does the Sun look like the Greek letter Omega? Atmospheric refraction. From the viewers perspective, the anomaly is caused by the deviation of sunlight from a straight line as it passes through the atmosphere due to the variation in air density as a function of height. This single exposure image was taken at sunrise over the Mediterranean Sea near Valencia, Spain.