Arecibo message
1974 AD

An interstellar radio message carrying basic information about humanity and Earth that was sent to space. It was meant as a demonstration of human technological achievement, rather than a real attempt to enter into a conversation with extraterrestrials.

The content of the Arecibo message was designed by Frank Drake, then at Cornell University and creator of the Drake equation, who wrote the message with help from Carl Sagan and others. It consists of seven parts that encode the following (from the top down in the image):

• The numbers one to ten (white)
• The atomic numbers of the elements hydrogen, carbon, nitrogen, oxygen, and phosphorus, which make up deoxyribonucleic acid (DNA) (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) of an average man (blue/white), a graphic figure of a human being (red), and the human population of Earth (white)
• A graphic of the Solar System, indicating which of the planets the message is coming from (yellow)
• A graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish (purple, white, and blue)

When translated into graphics, with colors, characters, and spaces, the 1,679 bits of data contained within the message form the image shown here.