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When the NASA astronauts first landed on the Moon, they left a few items on the surface to commemorate their visit. These items included a plaque, mission badges and an American flag. If you’ve ever seen images or video of the flag on the Moon, you might have a few questions.
Why does the flag stand straight out and not just slump down? Here on Earth, flags are pushed out by the wind. Obviously, there’s no wind on the Moon, so what’s holding the flag up? The answer is pretty easy. There’s a rod, sort of the like a curtain rod running across the top. So the flag on the Moon is being held out by the rod and isn’t blowing in the wind.
What makes the flag flap if there’s no wind? You might have also see a few videos of the flag on the Moon waving back and forth. This happened when the astronauts first planted the flag. There’s no wind to make the flag to flag, but there’s also no wind to stop it from moving back and forth. When the astronauts planted the flag on the Moon, they couldn’t help but give it a sideways push. Without the wind resistance the flag would experience on the Earth, the flag can flap back and forth a few times before finally settling down. That’s why it looks like it’s flapping, even though there’s no wind.
There’s another scene where the flag flaps, as the lunar ascent module is taking off. In this case, the exhaust from the rocket is blasting the flag and causing it to flap back and forth. In the case of Apollo 11, the exhaust blast was so strong that the flag actually fell over. Later missions kept the flag much further away from the ascent rocket.
Can we see the flag on the Moon from Earth with a big telescope, or even Hubble? Even though we have some powerful telescopes, they’re just not powerful enough to spot objects the size of a flag on the surface of the Moon. The flag is only a meter across. In fact, you would need a telescope 200 meters across to spot objects that size from here on Earth. Future space missions will return to the Moon, and they should be able to resolve objects as small as the flags on the Moon.
Does the flag mean that the US claims the Moon? Nope, the Moon can’t be owned by anyone. NASA had the astronauts plant the flag to commemorate the journey made by American astronauts, but to not actually claim the Moon for any single nation.
We’ve done a few articles about this topic. Here’s a review of the Mythbusters episode where they debunk the Moon flag myth.
NASA has answered some more questions about the flag on the Moon. Here’s a link to their article. And here’s another article debunking the conspiracy theory that NASA didn’t even go to the Moon.
You can listen to a very interesting podcast about the formation of the Moon from Astronomy Cast, Episode 17: Where Did the Moon Come From?