On November 16th, 1974 the Arecibo telescope was used to send a message in the direction of the Hercules constellation. More specific in the direction op Globular Star Cluser Messier M13.
M13 contains approximately 300.000 stars and is located at a distance of 25.000 light years from Earth.
The message is build around 1679 pulses of binary codes (zero and one's) and contains information about our numerical system, chemical elements, human beings, our planet, our solarsystem and the telescope itself. It was sent by the Arecibo telescope using radio signals.