Before it was transmitted toward M13, the author of the message, Frank Drake, first beamed it on paper to Carl Sagan over lunch at the faculty club at Cornell University. Prof. Sagan quickly figured out almost all of the message--can you? (This is not an idle puzzle--consider that when Frank Drake handed the message to Carl Sagan the two had known each other and collaborated on various projects for more than a decade, and thus shared a context which would help in decoding the message. If you're seeing this for the first time, you may genuinely learn something about the difficulty in establishing communications with a truly alien being by trying to figure out what Frank Drake so earnestly encoded into the bits of this message.) ...
'CROPCIRCLE' ARECIBO MESSAGE
...This is where a slight puzzle becomes visible. By performing the steps described above, the literal translation of the original pulses is on the left of figure 3. However, the image printed in a couple of my books is that shown on the right of figure 3. This is an exact left-right mirror image of my decoding. I suspect that this is possibly an error which went un-noticed when the book went to print - although I have checked two books which both depict the same pattern as shown on the right of figure 3.
Try doing THAT with piece of string and a stick...