On the evening of July 3rd, 2020, Richmond Hill resident Ian Shelton captured this image while watching the setting Sun beautifully illuminate the top of a huge distant storm cloud. When sunlight needs to travel horizontally through many additional thicknesses of our atmosphere to reach our eyes or a distant object like the cloud shown here, air molecules can scatter most of the blue sunlight out of the beam, leaving just the yellows, oranges and reds of sunlight to illuminate us or a distant cloud. Contrast this with the unfiltered white sunlight traveling directly through space to reach the Waxing Gibbous Moon seen above and ten thousand times further away than the terrestrial cloud top.
Two days later, Dr. Shelton was joined by several other member of the DDO Defenders to watch the now Full Moon pass into Earth’s shadow. Unlike a more familiar umbral lunar eclipse where a dark circular shadow makes part or all of a Full Moon seem to disappear, a penumbral eclipse is a much more subtle event that is easily missed. Encircling the cone-shaped dark inner “umbral” shadow cast by the Earth is the “penumbra”, a larger outer cone where only partial darkness occurs. On July 5th, the Moon passed 30% of the way into the penumbral cone, causing only about 20% darkening towards the north edge of the Moon.
By eye, the event went unnoticed. But it was captured photographically, as shown in the image here. A photograph taken just before the eclipse began was subtracted from a photograph taken at mid-eclipse.
-DDO Defenders 🙂