Hear Ye! Since 1998.
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Aug 01

Celestial Art

This guy wants to paint a big red dot onto the moon by shining millions of laser pointers at it. The web site calls upon people in America to aim their pointers at the moon for a five minute period. Unfortunately, the guy’s right when he said that he is not a scientist. While laser light does stay coherent and is highly directable, the light still attenuates – especially through the earth’s atmosphere. Strictly speaking, although the light never really becomes “invisible”, it does diminish in intensity out of the range of human sight – invisible to us, in other words. Most household laser pointers have a visible range of, at most, a couple kilometres. The moon is a fair bit further than that. Additionally, the area of the moon that would have to be lit up to be visible to the human eye would be impractically large. I think in Australia, there is also some law that prohibits general-use laser pointers over a certain power (1 milliwatt I think). The US probably has similar laws relating to safety regulations and lasers. It’s a quaint sentiment overall, but one unlikely to work.