One of the first things the Apollo astronauts noticed while exploring the surface of the Moon was how dark the shadows were. On the Moon, shadows were almost pitch black – much darker than on Earth. The astronauts struggled with perception while setting up experiments, but over time their eyes and brains adapted to the new conditions.
The reason for the dark shadows? Unlike on Earth, there’s no air on the Moon to refract light and provide additional illumination. This makes it very difficult to discern the details of objects on the lunar surface that aren't in direct sunlight.
Casting light on lunar shadows:
- Part of the problem is the amount of available light on the Moon. Sunlight reflected off the Moon’s rounded terrain provides some weak illumination, as does light reflected from the Earth – but far less than a normal day on our planet.
- Encountering tiny shadows in unexpected places confounded astronauts for the duration of the Apollo program, making working on things like bolts and gauges a challenge. But mostly these were minor nuisances.
- Buzz Aldrin and Neil Armstrong both described an otherworldly phenomenon on the lunar surface. When looking at the shadows of their own heads, they noticed a strange glow. "(There's) a halo around the shadow of my helmet," Aldrin reported.