The sourced background on Arecibo message.

The Arecibo message is an interstellar radio message carrying basic information about humanity and Earth that was sent to the globular cluster Messier 13 (M13) in 1974.

The Arecibo message is an interstellar radio message carrying basic information about humanity and Earth that was sent to the globular cluster Messier 13 (M13) in 1974. It was meant as a demonstration of human technological achievement rather than a real attempt to enter into a conversation with extraterrestrials.