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This is the message with color added to highlight its separate parts. The actual binary transmission carried no color information.

The Arecibo message is a radio message that was beamed into space at a ceremony to mark the remodeling of the Arecibo radio telescope on 16 November 1974.^[1] It was aimed at the globular star cluster M13 some 25,000 light years away because it was a large and close collection of stars that was available in the sky at the time and place of the ceremony.^[2] The message consisted of 1679 binary digits (equivalent to nearly 210 bytes, since (1679 / 8) = 209.87 (8 bits in 1 byte)) transmitted at a frequency of 2380 MHz and modulated by shifting the frequency by 10 Hz, with a power of 1000kW.^[1] The beam was extremely narrow (giving a power equivalent to 20TW if it were omnidirectional) making it the strongest man-made signal ever sent. The entire transmission lasted 1679 seconds and was not repeated.^[3] The number 1679 was chosen because it is a semiprime (the product of two prime numbers) and therefore can only be broken down into 23 rows and 73 columns, or 73 rows and 23 columns. This assumes that those who read it will choose to arrange it as a rectangular raster scan. The information arranged the first way (23 rows, 73 columns) produces jumbled nonsense, but if arranged the second way (73 rows, 23 columns) it forms the image shown on the right (assuming the bits are arranged from left to right and the rows are arranged from top to bottom; otherwise a flipped image is formed), which is assumed to be recognizable as data.^[4] Image File history File links Question_book-3. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The Arecibo Observatory is located approximately 9 miles south-southwest from Arecibo, Puerto Rico (near the extreme southwestern corner of Arecibo pueblo). ... is the 320th day of the year (321st in leap years) in the Gregorian calendar. ... Year 1974 (MCMLXXIV) was a common year starting on Tuesday (link will display full calendar) of the 1974 Gregorian calendar. ... Messier Object 13, the Great Globular Cluster in Hercules; one of the most prominent and best known globular clusters of the Northern celestial hemisphere. ... A light-year or lightyear (symbol: ly) is a unit of measurement of length, specifically the distance light travels in vacuum in one year. ... This article is about the unit of information. ... The kilowatt (symbol: kW) is a unit for measuring power, equal to one thousand watts. ... In radio telecommunications, effective radiated power (ERP) is determined by subtracting system losses and adding system gains to the actual electrical power output of a transmitter. ... This page lists examples of the power in watts produced by various different sources of energy. ... In mathematics, a semiprime (also called biprime or 2-almost prime, or pq number) is a natural number that is the product of two (not necessarily distinct) prime numbers. ... In mathematics, a prime number (or a prime) is a natural number greater than 1 which has exactly two distinct natural number divisors: 1 and itself. ... Raster can refer to either of the following items: Raster graphics, Bit array, the general-purpose data structure, or The scanning pattern of the electron beam to a screen of a Cathode Ray Tube. ...

The Arecibo message if it were decoded as 73 rows and 23 columns.

Reading the image from top to bottom and left to right, it can be divided into 7 parts that state (or show) 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 man, the dimension (physical height) of an average man, and the human population of Earth
6. a graphic of Earth's solar system
7. a graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish

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 that that message was aimed at will no longer be there when the message arrives.^[1] According to the Cornell News press release of Nov. 12, 1999, the real purpose of the message was not to make contact, but to demonstrate the capabilities of newly installed equipment.^[1] In chemistry and physics, the atomic number (Z) is the number of protons found in the nucleus of an atom. ... This article is about the chemistry of hydrogen. ... For other uses, see Carbon (disambiguation). ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... This article is about the chemical element and its most stable form, or dioxygen. ... General Name, symbol, number phosphorus, P, 15 Chemical series nonmetals Group, period, block 15, 3, p Appearance waxy white/ red/ black/ colorless Standard atomic weight 30. ... DNA replication Deoxyribonucleic acid (DNA) is a nucleic acid which carries genetic instructions for the biological development of all cellular forms of life and many viruses. ... In mathematics and in the sciences, a formula (plural: formulae, formulæ or formulas) is a concise way of expressing information symbolically (as in a mathematical or chemical formula), or a general relationship between quantities. ... This article is about sugar as food and as an important and widely-traded commodity. ... Acids and bases: Acid-base extraction Acid-base reaction Acid dissociation constant Acidity function Buffer solutions pH Proton affinity Self-ionization of water Acids: Lewis acids Mineral acids Organic acids Strong acids Superacids Weak acids Bases: Lewis bases Organic bases Strong bases Superbases Non-nucleophilic bases Weak bases edit In... A nucleotide is an organic molecule consisting of a heterocyclic nucleobase (a purine or a pyrimidine), a pentose sugar (deoxyribose in DNA or ribose in RNA), and a phosphate or polyphosphate group. ... This article is about the Solar System. ... The Arecibo Observatory is located approximately 9 miles south-southwest from Arecibo, Puerto Rico (near the extreme southwestern corner of Arecibo pueblo). ...

Dr. Frank Drake, then at Cornell University and creator of the famous Drake equation, wrote the message, with help from Carl Sagan, among others.^[1] Whether or not this message has any ostensible effects, it has nevertheless forced humanity to consider how it might communicate with extrasolar beings, and what the contents of any such communications might be. Professor Frank Drake Frank Drake (born May 28, 1930, Chicago, Illinois) is an American astronomer and astrophysicist. ... Cornell redirects here. ... The Drake equation (also sometimes called The Green Bank equation, The Green Bank Formula or often erroneously labeled The Sagan equation) is a famous result in the speculative fields of exobiology and the search for extraterrestrial intelligence (SETI). ... Insert non-formatted text here Carl Edward Sagan (November 9, 1934 – December 20, 1996) was an American astronomer and astrobiologist and a highly successful popularizer of astronomy, astrophysics, and other natural sciences. ...

Explanation

Numbers

 1 2 3 4 5 6 7 8 9 10 ---------------------- 0 0 0 1 1 1 1 00 00 00 0 1 1 0 0 1 1 00 00 10 1 0 1 0 1 0 1 01 11 01 X X X X X X X X X X <-least-significant-digit marker 

The numbers from 1 to 10 appear in binary format (the bottom row marks the beginning of each number). This article is about the number one. ... This article is about the number 10. ... The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ...

Even knowing binary, the encoding of the numbers may not be immediately obvious due to the way they have been written. To read the first seven digits, ignore the bottom row, and read them as three binary digits from top to bottom, with the top digit being the most significant.

The readings for 8, 9 and 10 are a little different, as they have been given an additional column next to the first (to the right in the image). This is probably intended to show that numbers too large to fit in a column can be written in several contiguous ones, where the contiguous columns do not have the base marker.

DNA elements

 H C N O P 1 6 7 8 15 ---------- 0 0 0 1 1 0 1 1 0 1 0 1 1 0 1 1 0 1 0 1 X X X X X 

The numbers 1, 6, 7, 8 and 15 appear. These are the atomic numbers of hydrogen (H), carbon (C), nitrogen (N), oxygen (O), and phosphorus (P), the components of DNA. This article is about the chemistry of hydrogen. ... For other uses, see Carbon (disambiguation). ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... This article is about the chemical element and its most stable form, or dioxygen. ... General Name, symbol, number phosphorus, P, 15 Chemical series nonmetals Group, period, block 15, 3, p Appearance waxy white/ red/ black/ colorless Standard atomic weight 30. ...

The numbers 8 and 15 are written in a logical extension of binary encoding, rather than with the contiguous-columns method shown in the message's number figures at the top:

Nucleotides

 Deoxyribose Adenine Thymine Deoxyribose (C5OH7) (C5H4N5) (C5H5N2O2) (C5OH7) 

 Phosphate Phosphate (PO4) (PO4) 

 Deoxyribose Cytosine Guanine Deoxyribose (C5OH7) (C4H4N3O) (C5H4N5O) (C5OH7) 

 Phosphate Phosphate (PO4) (PO4) 

Deoxyribose Deoxyribose, also known as D-Deoxyribose and 2-deoxyribose, is an aldopentose — a monosaccharide containing five carbon atoms, and including an aldehyde functional group. ... For the programming language Adenine, see Adenine (programming language). ... For the similarly-spelled vitamin compound, see Thiamine Thymine, also known as 5-methyluracil, is a pyrimidine nucleobase. ... A phosphate, in inorganic chemistry, is a salt of phosphoric acid. ... Cytosine is one of the 5 main nucleobases used in storing and transporting genetic information within a cell in the nucleic acids DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an amine group at position 4 and a keto group at... Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA; the others being adenine, cytosine, thymine, and uracil. ...

The nucleotides are described as sequences of the five atoms that appear on the preceding line. Each sequence represents the molecular formula of the nucleotide as incorporated into DNA (as opposed to the free form of the nucleotide). A nucleotide is an organic molecule consisting of a heterocyclic nucleobase (a purine or a pyrimidine), a pentose sugar (deoxyribose in DNA or ribose in RNA), and a phosphate or polyphosphate group. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ...

For example, deoxyribose (C₅OH₇ in DNA, C₅O₄H₁₀ when free), the nucleotide in the top left in the image, is read as:

 11000 10000 11010 XXXXX ----- 75010 

i.e. 7 atoms of hydrogen, 5 atoms of carbon, 0 atoms of nitrogen, 1 atom of oxygen, and 0 atoms of phosphorus.

Double helix

 11 11 11 11 11 01 11 11 01 11 01 11 10 11 11 01 X 

 1111111111110111 1111101101011110 (binary) = 4,294,441,822 (decimal) 

DNA double helix (the vertical bar represents the number of nucleotides, but the value depicted is around 4.3 billion when in fact there are about 3.2 billion base pairs in the human genome). A helix (pl: helices), from the Greek word έλικας/έλιξ, is a twisted shape like a spring, screw or a spiral (correctly termed helical) staircase. ...

Humanity

 X011011 111111 X0111 110111 111011 111111 110000 

 1110 (binary) = 14 (decimal) 

 000011 111111 110111 111011 111111 110110 (binary) = 4,292,853,750 (decimal) 

The element in the center represents a human. The element on the left (in the image) indicates the average height of a person: 1764 mm. This corresponds to the horizontally written binary 14 multiplied by the wavelength of the message (126 mm). The element on the right depicts the size of human population in 1974, around 4.2 billion. In this case, the number is oriented horizontally rather than vertically, with the least-significant-digit marker to the upper left in the image. A millimetre (American spelling: millimeter, symbol mm) is an SI unit of length that is equal to one thousandth of a metre. ... For other uses, see Wavelength (disambiguation). ...

Planets

 Earth Sun Mercury Venus Mars Jupiter Saturn Uranus Neptune Pluto 

The solar system, showing the Sun and the planets in the order of their position from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. (Pluto is now classified as a dwarf planet, but was still considered a planet at the time the message was written.) This article is about the Solar System. ... Sol redirects here. ... Sol redirects here. ... This article is about the planet. ... (*min temperature refers to cloud tops only) Atmospheric characteristics Atmospheric pressure 9. ... This article is about Earth as a planet. ... Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... Atmospheric characteristics Atmospheric pressure 120 kPa Hydrogen 83% Helium 15% Methane 1. ... Atmospheric characteristics Surface pressure ≫100 MPa Hydrogen - H2 80% ±3. ... For other uses, see Pluto (disambiguation). ... Artists impression of Pluto (background) and Charon (foreground). ...

The Earth is the third planet from the Sun - its graphic is shifted up to identify it as the planet from which the signal was sent. The human figure is shown "standing on" the Earth graphic. Sol redirects here. ...

In addition to showing position, the graphic provides a general, not-to-scale size reference of each planet and the Sun.

Telescope

 bottom two rows: 100101 <--- 111110X ---> 

 100101 111110 (binary) = 2,430 (decimal) 

The last part represents the Arecibo radio telescope with its diameter (2430 multiplied by the wavelength gives 306.18 m). In this case, the number is oriented horizontally, with the least-significant-digit marker to the lower right in the image. The Arecibo Observatory is located in Arecibo, Puerto Rico on the north coast of the island. ... DIAMETER is a computer networking protocol for AAA (Authentication, Authorization and Accounting). ... This article is about the unit of length. ...

See also

• Communication with Extraterrestrial Intelligence
• Active SETI
• Arecibo reply
• Interstellar Radio Messages

CETI (Communication with Extraterrestrial Intelligence, or METI, Messaging to Extraterrestrial Intelligence) is a branch of SETI research that focuses on composing and deciphering messages that could theoretically be understood by another technological civilization. ... A representation of the 1679-bit Arecibo message. ... Arecibo reply crop circle The Arecibo reply was the name given to a crop circle that appeared in farmland next to the Chilbolton radio telescope; home to the Search for Extraterrestrial Intelligence Institute (SETI) in Hampshire, UK, on 19 August 2001. ...

References

2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance with the Gregorian calendar. ... is the 88th day of the year (89th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 208th day of the year (209th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 125th day of the year (126th in leap years) in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 208th day of the year (209th in leap years) in the Gregorian calendar. ...

External links

• SETI homepage on the message
• Interstellar Radio Messages
• Arecibo Observatory message on Alien Research
• Cornell news: Arecibo message anniversary
• Ithaca Times article on 31st anniversary of Arecibo Message broadcast.
• The Arecibo Message explained