Crop circles and π

Baffling crop circles equal pi.

The main thing here is a picture of a crop circle which encodes the first ten decimal digits of π. The article doesn't explain how, but I will. "Read" from the inside out; notice that the main part of the figure consists of ten concentric arcs joined by short segments. The arcs have angular lengths 3, 1, 4, 1, 5, 9, 2, 6, 5, and 4 tenths of a circle.

The article says that "This may cause more controversy in the debate whether crop circles are a result of extraterrestrial activity." It seems to me evidence against extraterrestriality; there's no reason why extraterrestrials would use decimal. The usual hypothesis seems to be that if aliens want to send us numbers, they'll do so in binary; this seems reasonable because 2 is really the only "special" numerical base, being the smallest practically usable one. (You can't send arbitrary real numbers in "base 1", and the time to send the integer N scales like N, as opposed to like log N in any base greater than 1.

And I thought that crop circles had pretty thoroughly been shown to be the work of human pranksters.

Of course, a much simpler way to encode π in a circle is to just have the circle itself.