Moon trails

Summary Authors: Nikos Paschalis; Jim Foster (EPOD)The image above is a time lapse (opens in a new tab) of the full Moon (opens in a new tab) rising over Skiathos Island (opens in a new tab) (in the background), Greece. It’s composed of approximately 20 frames taken 30 seconds apart on the evening of April 25, 2013. Note that the Moon (opens in a new tab) subtends the same angle of the sky (1/2 degree) during its rise -- it’s not any bigger when it breaks the horizon than it is when well up in the sky. However, the color of the Moon does change as moonrise progresses from red to orange to yellow to white. These color changes are attributed to changes in the path length (opens in a new tab) of moonlight that reaches our eyes. Red colors (long wavelengths of visible light) result from the longer path lengths when the Moon (opens in a new tab) is very low in the sky. As the Moon (opens in a new tab) rises higher and higher, our atmosphere scatters the longer wavelengths about as much as the shorter wavelengths, so the Moon (opens in a new tab) appears white.