Cornell, which manages the Arecibo Radio Observatory on the island of Puerto Rico for the National Science Foundation (NSF), conducted a major upgrade to the facility in 1974. To celebrate this event, Frank Drake, then a Professor of Astronomy at Cornell, along with several graduate students from the university and the celebrated astronomer and fellow Cornell astronomy professor Carl Sagan, devised a message that would be broadcast from the 1,000-foot wide radio telescope into the Milky Way Galaxy during the upgrade dedication ceremony on November 16, 1974.
The Arecibo Message, as it has come to be known, was a relatively simple pictogram encoded into 1,679 binary data bits of ones and zeros. With the ones representing the image characters and the zeros blank spaces, anyone smart enough will be able to produce the message, the first ever deliberately sent by humanity to fellow intelligences in the galaxy.
What Does It Say?
While it was impossible to know exactly who or what might detect the Arecibo Message some day, the Cornell scientists knew that the recipients would have to be at least at our level of intelligence and technology to find it. These parameters also meant that they would have to possess a literally universal understanding of mathematics and science, a requirement of any technology-based civilization.
Going on this concept, the message began with a binary representation of the numbers one to ten. This would give the recipients a basis to comprehend the rest of the message.
The next set of binary bits in the message is the atomic numbers for five of the most common and abundant elements that make up all life as we know it: hydrogen, carbon, nitrogen, oxygen, and phosphorus. Perhaps most all organic life in the Universe is some combination of these same elements.
The other parts of the Arecibo Message consist of a diagram and the chemical makeup of deoxyribonucleic acid (DNA) the genetic code found in every cell of all Earth life. Will the beings who decipher this introductory lesson in terrestrial biology recognize the double helix of DNA and its components as part of their own makeup? Or will it make us seem even more alien to them?
Attached both literally and symbolically to the bottom of the DNA helix is a stick figure representation of a human being. The figure is surrounded on either side by binary numbers indicating the average height of a human being (5 feet, 9.5 inches) and the total number of people on Earth at the time of the message's sendoff - which was two billion less than the current figure of over six billion just three decades later!
Beneath the feet of the human figure is a representation of the Sun and major planets of our Solar System, with Earth knocked up a notch to indicate to the recipients that this is the home world of the message senders. The final part of the cosmic postcard displays a rough diagram of the Arecibo radio telescope which broadcast it into deep space and the giant dimensions of the dish.
Where is the Message Going?
The astronomers decided to aim the message at a large and close collection of stars that were available at the time of day and place during the dedication ceremony. The object chosen was the globular star cluster known as Messier 13, a relatively tight group of hundreds of thousands of suns 165 light years across and more than 25,000 light years distant (one light year equals about 6 trillion miles; now times the 6 trillion by 25,000 to get the mileage).
As the radio message travels at the speed of light (186,000 miles per second), it will currently reach Messier 13 and all its suns in just under 25,000 years.
This naturally means that a response from anyone there will take another 25,000 years to get back to our distant descendants, or whoever may be occupying Earth by then.
The gesture made by those Cornell astronomers back in 1974 was largely symbolic, but should the Arecibo Message be received by someone someday somewhere out there, the results could literally gain us and the recipients a whole new perspective on our place in the Cosmos.
For a visual representation of the Arecibo Message and more details on its contents and destination, visit http://en.wikipedia.org/wiki/Arecibomessage.