When the Apollo astronauts stepped out onto the lunar surface, they were the first human eyes to see this alien landscape. And one of the strangest things that they saw were the shadows. On Earth, our shadows aren't black, but blue, thanks to the scatter light passing through our atmosphere. But on the Moon, which has no atmosphere, the shadows are utterly black. The darkness of the shadows was one of the first things that Neil Armstrong noticed as he stepped off the lunar module and onto the surface of the Moon.