Arecibo message and decoded key. Diagram showing the binary transmission (left) known as the Arecibo message, with the message decoded and labelled at centre and right. This message was broadcast on 16 November 1974 by the Arecibo radio telescope in Puerto Rico, USA. The message was aimed at the M13 globular star cluster (25,000 light years distant). The broadcast lasted less than three minutes and consisted of 1679 binary digits. The seven parts of the message were (from top): the numbers 1-10, elemental atomic numbers for DNA, nucleotide formulae for DNA, double helix of DNA, a human figure, the solar system, and the transmitting telescope.