July 20, 1969, was a historic day in the history of mankind. It was the day when two astronauts of Apollo 11, Neil Armstrong and Buzz Aldrin (leaving behind poor Michael Collins) climbed down from the Eagle Lunar Module to put the first human footprints on the surface of the moon. That’s the story that the majority of us know (and believe). However, there is another side to this story as well. A vocal minority believes that this moon landing was filmed on a Hollywood set and is an elaborate hoax. Their evidence to prove the fact is the photographs and video footage that was shot when then landed on the lunar surface. Their argument is that those photos and video don’t show any stars in the sky.
How could Hollywood directors be so careless? In fact, the scientific explanation to this is pretty mundane – the camera settings weren’t adjusted to click them.
Let me explain this in a better way. Suppose you want to click a picture of your friend in direct sunlight; there are two ways in which you can adjust your camera settings. First, you would narrow the aperture which would restrict the entry of too much light entering into the lens: the same reason your pupils’ contract in bright light. Second, you would control the speed of the shutter to that camera sensor would only let in light for a brief moment. Now, if you want the same picture at night, you would slow down the shutter speed and widen the aperture, so that you let in enough light.
Now, assume that somehow this friend of yours arranges some extra lighting and stays illuminated even at night time. Then how would you click the photo? If you want to include the stars in the background, you would need to ensure that your friend stays extra still to avoid the blurring the shot with slow shutter speed and wide aperture. On contrary, if you keep the aperture small and shutter speed high, you’ll get a sharp and decently bright picture of your friend but the only issue would be that the background would be dark as it would not be able to send enough light into the lens.
This is the trade-off that Apollo 11 astronauts had to make. The sky on the moon is black as it is in the night on Earth not because it is night there, but because the moon has no atmosphere to scatter the daylight the way ours does on Earth. But keep in mind, there is as much as sunlight at noon on the moon as there is on the Earth. This is what makes the lunar surface bright. We were very much interested in the lunar scenery, so the cameras on Apollo 11 were adjusted to make most out of it. Consequently, the dim stars in the background didn’t get clicked in any of the shots. No hoax: just a basic and small camera lens trick.