If you were to write in the dust on the moon, how big would the letters have to be so you could see them from earth without a telescope?

Did you know that contrary to popular belief, the Great Wall of China is not viewable from outer space? The viewer would need visual acuity 17 times better than normal (20/20) to see the Wall from the Moon, and vision 8 times better than normal to see it from low earth orbit.

From their vantage point on the Moon, Apollo astronauts could not make out any man made features on Earth. They could make out oceans and land masses but not much more.

So subject to moon phases, this FAQer thinks that for writing on the moon to be visible from Earth, each letter would have to be at least half as big as the Mare Crisium which measures 345 miles in diameter therefore each letter would need to be at least 175 miles high.

Just ensure you write on the correct side...

Share

top ↑