The Arecibo Message

Most people either weren’t born or don’t remember that SETI (the Search for Extra-Terrestrial Intelligence) sent a message into space in 1974. It was an odd message, done in binary code but meant to be read as a sort of picto-gram. It was sent as a radio signal from the Arecibo radio telescope in Puerto Rico, beamed towards a star cluster far out in space. Here it is, deciphered, below:

The message consists of seven parts that encode the following (from the top down in the image):[4]

• The numbers one to ten (white; left to right)

• The atomic numbers of the five elements which make up our DNA, hydrogen, carbon, nitrogen, oxygen, and phosphorus (purple)

• The formulas for the chemical compounds that make up the nucleotides of DNA (green)

• The estimated number of DNA nucleotides in the human genome, and a graphic of the double helix structure of DNA (white and blue, respectively)

• The dimension (physical height, 5'9") of an average man (blue/white), a graphic figure of a human being (red), and the human population of Earth which was about 4 billion at the time (white)

• A graphic of the Solar System, indicating which of the planets the message is coming from (yellow). The Sun is on the left and the third planet, Earth, raised toward the human figure

• A graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish (purple, white, and blue)

Wow. Who would have figured that one out? The answer was, SETI hoped, intelligent people with a foundation in mathematics. However, it was expected to take something like 25,000 years (it was a radio signal) to reach the star cluster it was aimed at, so they weren’t exactly waiting with baited breath.

But here’s the thing: someone answered.