Differences in Landscape Brightness During a Lunar Eclipse

January 23, 2011

Photographer: Edwin Proctor
Summary Author
: Edwin Proctor; Dave Lynch

It's frustrating when you're anticipating an event like an eclipse and the weather doesn't cooperate. Sometimes you have to improvise and hope something of interest comes out of it. On the night of December 21, 2010, during the early morning hours, I had planned to view the total "solstice" lunar eclipse, but a snowstorm where I live in Madison, Wisconsin quickly made it clear that the Moon would be impossible to observe. However, I began to wonder if I could see the red shift (reddening or darkening of the Moon during the eclipse) in the snow outside of my home. I did a custom color balance on the snow and then took a series of images to see if the color changed as the eclipse progressed. Then, without changing any settings, I created a sliced image in Photoshop to see if there was a difference. The result is shown in the sequence above. The slice at far right was captured when the lunar disk was fully eclipsed. Am I really seeing a change, or is something else going on?

Note that the custom color frame was made before the eclipse started; therefore it was lit by the full Moon as well as by a street light and other ambient light in the neighborhood. As the eclipse progressed, the amount of light from the Moon would have decreased in relation to the amount of light from all other sources. As it did, the decreasing level of white (or moonlight) caused the increasing percentage from other sources to become more visible. So, what I have is "tinted" not because it's from the Moon but rather because the light from the Moon is not there. Had I continued with the slices for the duration of the eclipse, I suspect the color balance would have come back to white as the shadow passed away from the Moon. Frame 1238 (0038) is likely brighter relative to adjacent frames due to the thickness of the clouds in the passing storm. Times are indicated on the bottom of each slice -- 23:15 is 11:15 p.m. and 0038 is 12:38 p.m. (38 minutes past midnight).

Photo details: Canon 50D camera; 17 mm lens; ISO 1000; exposure 1.3 Seconds; f5.6; times on image are Central Standard Time.