Hear Ye! Since 1998.
Please note: This post is at least 3 years old. Links may be broken, information may be out of date, and the views expressed in the post may no longer be held.
10
Aug 01
Fri

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.