Arecibo message
It was a message signal transmitted into space via frequency modulated radio waves toward the star cluster M13. The message was broadcasted at a ceremony to mark the remodeling of the Arecibo radio telescope on 16 November 1974. It was transmitted to the globular star cluster M13 (some 25,000 light years away) because M 13 was a large and close collection of stars that was available in the sky at the time and place of the ceremony.
The message mainly Consisted of 1679 binary digits, approximately 210 bytes, Transmitted at a frequency of 2380 MHz Modulated by shifting the frequency by 10 Hz, With a power of 1000 kW. The "ones" and "zeros" were transmitted at the rate of 10 bits per second (by frequency shifting).
Total broadcast was less than three minutes. Dr. Frank Drake wrote the message, with help from Carl Sagan, among others.
The message consists of seven parts that encode the following:
1. The numbers one (1) through ten (10)
2. The atomic numbers of the elements hydrogen, carbon, nitrogen, oxygen, and phosphorus, which make up deoxyribonucleic acid (DNA)
3. The formulas for the sugars and bases in the nucleotides of DNA
4. The number of nucleotides in DNA, and a graphic of the double helix structure of DNA
5. A graphic figure of a human, the dimension (physical height) of an average man, and the human population of Earth
6. A graphic of the Solar System
7. A graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish
The cardinality of 1679 was chosen because it is a semiprime(the product of two prime numbers), to be arranged rectangularlyas 73 rows by 23 columns. The alternative arrangement, 23 rows by 73 columns, produces jumbled nonsense. The message forms the image shown on the right, or its inverse, when translated into graphics characters and spaces. Because it will take 25,000 years for the message to reach its intended destination of stars (and an additional 25,000 years for any reply), the Arecibo message was more a demonstration of human technological achievement than a real attempt to enter into a conversation with extraterrestrials. In fact, the stars of M13 that the message was aimed at will no longer be in that location when the message arrives. According to the Cornell News press release of November 12, 1999, the real purpose of the message was not to make contact, but to demonstrate the capabilities of newly installed equipment.