You'll be hearing a lot about the super moon today, because the moon is closer to Earth than it has been in almost 69 years. At 14%, it won't look a whole lot bigger, though. "Super-sized" is not what comes to mind...more like "oh yeah, I can see how that kind of looks bigger." The most noticeable thing when we checked it out last night was that it seemed WAY brighter. The shadows caused by the moon last night were super crisp and sharp. My kids initially thought the shadows were being caused by some electric light and they were awestruck to learn they were created by the moon. (Then again, this could just be because we don't spend enough time outside at night.)
Illuminance at a point can be simply calculated as a function of luminous intensity divided by distance squared. So the illuminance on the surface of the earth will vary inversely with the square of the distance from the moon. The equation is E=I/d^2. What exactly does this mean? The amount of light that reaches us is not a straight relationship with our distance from the moon. The light is doubly-impacted by the distance. Do you think you can tell the difference? Check it out tonight and let us know!
Lisa J. Reed, lighting designer and Principal at Envision Lighting Design, LLC