Arecibo message

The Arecibo message was an interstellar radio message, sent in the direction of the star cluster M13 in the constellation of the Hercules in 1974. It was designed in the hopes an extraterrestrial intelligence would be able to decipher it, and learn some basic information about humanity and the planet Earth.

The message consisted of 1679 binary digits, a number chosen because it is the product of two prime numbers, allowing it to be assembled to a rectangle in only one way.

The parts of the message are as follows:

It will take approximately 25000 years for the message to arrive at its intended destination - and an additional 25000 years for any reply.