Why doesn’t Earth’s shadow on the moon look red during a partial lunar eclipse?
Once again, you need to build an argument based on geometry, but now you must consider the direction of sunlight. During a partial lunar eclipse, part of the moon protrudes from Earth’s umbral shadow into sunlight. This part of the moon is very bright compared to the fainter red light inside Earth’s shadow, and the glare of the reflected sunlight makes it difficult to see the red glow. If a partial eclipse is almost total, so that only a small sliver of moon extends out of the shadow into sunlight, you can sometimes detect the red glow in the shadow. Of course, this red glow does not happen for every planet–moon combination in the universe. Adapt your argument for a new situation. Would a moon orbiting a planet that had no atmosphere glow red during a total eclipse? Why or why not? Connections : Lunar eclipses are slow and stately. For drama and excitement, there is nothing like a solar eclipse, as you will discover in the next section.
