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. The Arecibo Observatory is a very sensitive Radio telescope located approximately south-southwest from the town of Arecibo in Puerto Rico. Events 534 - A second and final revision of the Codex Justinianus is published Year 1974 ( MCMLXXIV) was a Common year starting on Tuesday (link will display full calendar of the 1974 Gregorian calendar. ^[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. The Great Globular Cluster in Hercules (also known as the Hercules Globular Cluster, Messier Object 13, Messier 13, M13, or NGC 6205 A light-year or light year (symbol ly) is a unit of Length, equal to just under ten trillion Kilometres As defined by ^[2] The message consisted of 1679 binary digits (equivalent to nearly 210 bytes, since (1679 / 8) = 209. A bit is a binary digit, taking a value of either 0 or 1 Binary digits are a basic unit of Information storage and communication 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. The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. ^[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. In radio Telecommunications, effective radiated power or equivalent radiated power (ERP is a standardized theoretical measurement of radio frequency (RF The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. 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. In Mathematics, a semiprime (also called biprime or 2- Almost prime, or pq number) is a Natural number that is the product In Mathematics, a prime number (or a prime) is a Natural number which has exactly two distinct natural number Divisors 1 This assumes that those who read it will choose to arrange it as a rectangular raster scan. A Raster scan, or raster scanning, is the pattern of image detection and reconstruction in television and is the pattern of image storage and transmission used in most computer 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]

The Arecibo message if it were decoded as 23 rows and 73 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. See also List of elements by atomic number In Chemistry and Physics, the atomic number (also known as the proton Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known In Mathematics and in the Sciences a formula (plural formulae, formulæ or formulas) is a concise way of expressing information Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. In Chemistry, a base is most commonly thought of as an aqueous substance that can accept Protons This refers to the Brønsted-Lowry theory of acids and Nucleotides are Organic compounds that consist of three joined structures a nitrogenous base a Sugar, and a Phosphate group The Solar System consists of the Sun and those celestial objects bound to it by Gravity. The Arecibo Observatory is a very sensitive Radio telescope located approximately south-southwest from the town of Arecibo in Puerto Rico. 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]

Dr. Frank Drake, then at Cornell University and creator of the famous Drake equation, wrote the message, with help from Carl Sagan, among others. Dr Frank Donald Drake (born May 28 1930, Chicago) is an American Astronomer and Astrophysicist. The Drake equation (also sometimes called the "Green Bank equation" the "Green Bank Formula" or often erroneously labeled the " Sagan equation" Carl Edward Sagan ( November 9 1934 &ndash December 20 1996) was an American Astronomer, astrochemist, author ^[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.

Explanation

Numbers

1 2 3 4 5 6 7 8  9  10----------------------0 0 0 1 1 1 1 00 00 000 1 1 0 0 1 1 00 00 101 0 1 0 1 0 1 01 11 01X 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). Mathematics For any number x: x ·1 = 1· x = x (1 is the multiplicative identity 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 P1 6 7 8 15----------0 0 0 1 10 1 1 0 10 1 1 0 11 0 1 0 1X 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. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15

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)

The nucleotides are described as sequences of the five atoms that appear on the preceding line. Deoxyribose, also known as D-Deoxyribose and 2-deoxyribose, is an Aldopentose &mdash a Monosaccharide containing five Carbon Adenine is a Purine with a variety of roles in Biochemistry including Cellular respiration, in the form of both the energy-rich Adenosine Thymine is one of the four bases in the Nucleic acid of DNA that make up the letters ATGC A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. Cytosine is one of the five main bases found in DNA and RNA. It is a Pyrimidine derivative with a Heterocyclic Aromatic ring Guanine is one of the five main Nucleobases found in the Nucleic acids DNA and RNA, the others being Adenine, Cytosine, Nucleotides are Organic compounds that consist of three joined structures a nitrogenous base a Sugar, and a Phosphate group Each sequence represents the molecular formula of the nucleotide as incorporated into DNA (as opposed to the free form of the nucleotide). A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes

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

110001000011010XXXXX-----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

11111111110111110111011110111101X

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. A helix (pl helixes or helices) from the Greek word έλιξ, is a special kind of Space curve, i 3 billion when in fact there are about 3. 2 billion base pairs in the human genome).

Humanity

        X011011         111111X0111    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. The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to This corresponds to the horizontally written binary 14 multiplied by the wavelength of the message (126 mm). In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. The element on the right depicts the size of human population in 1974, around 4. 3 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.

Planets

               EarthSun 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. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. The Sun (Sol is the Star at the center of the Solar System. The Sun (Sol is the Star at the center of the Solar System. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. (Pluto is now classified as a dwarf planet, but was still considered a planet at the time the message was written. A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded )

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 Sun (Sol is the Star at the center of the Solar System. The human figure is shown "standing on" the Earth graphic.

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. The Arecibo Observatory is a very sensitive Radio telescope located approximately south-southwest from the town of Arecibo in Puerto Rico. Geometry, a diameter of a Circle is any straight Line segment that passes through the center of the circle and whose Endpoints are on the 18 m). The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International In this case, the number is oriented horizontally, with the least-significant-digit marker to the lower right in the image.

See also

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

References

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