What Happened

In 1974, scientists at the Arecibo Observatory in Puerto Rico aimed their telescope at a distant star and fired a series of binary pulses. When aligned into a 23-pixel wide grid, these pulses form a crude picture - a message to the stars!

This message - this signal - became known as the Arecibo Signal.

Sadly, as cool as this was, it wasn't really an attempt to contact aliens.

It was just an elaborate way to celebrate mankind's technological achievements.

But, even so, it made history.

Decoding the Signal

A colored chart of the signal's binary code

To the left is an image of the Arecibo Signal, color coded to be easier to decipher.

Here is a breakdown of the different parts of the message, starting from the top of the image and working downwards:

The numbers 1 to 10
The atomic numbers of Hydrogen, Carbon, Nitrogen, Oxygen, and Phosphorus - the elements that make up DNA
The combinations of elements that make up the nucleotides in DNA
The number of nucleotides in the human genome (white)
The double helix structure of DNA (blue)
The average height of the average man (blue and white)
A crude image of a man (red, obviously)
The current population of the Earth (white)
A map of the solar system, highlighting Earth (yellow)
An image of the Arecibo Telescope (purple)
The dimensions of the telescope (blue and white)