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Arecibo message facts for kids

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"Arecibo Message" redirects here. For the 2009 Boxcutter album, see Arecibo Message (album).
Arecibo message
This is the message with color added to highlight its parts. The message carried no color information.

The Arecibo message was a short radio message sent into space to celebrate the remodeling of the Arecibo radio telescope in Puerto Rico in 1974. It was aimed at the globular star cluster M13, about 25,000 light years from Earth. M13 was chosen because it was the right size, and was in the sky at the right time and place for the ceremony.

Dr. Frank Drake, then at Cornell University and creator of the famous Drake equation, wrote the message, with help from Carl Sagan, among others. The message was in seven parts which show:

  1. The numbers one (1) to 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 figure of a human, the size of an average man, and the human population of Earth
  6. The Solar System
  7. The Arecibo Observatory and the diameter of the transmitting antenna dish

It will take 25,000 years for the message to reach the stars, and at least another 25,000 years to get any reply. This means the Arecibo message was a show of human technological achievement, not a real attempt to talk to extraterrestrial life. The stars of M13 that the message was aimed at will no longer be in that location when the message arrives. Cornell University said on November 12, 1999, the real purpose of the message was not to make contact, but to show the power of the new equipment. (Cornell University had built and operated the radio telescope for the United States National Science Foundation.)

The message consisted of 1679 binary digits, about 210 bytes. It was transmitted at a frequency of 2380 MHz and modulated by shifting the frequency by 10 Hz, with a power of 1000 kW. The "ones" and "zeros" were transmitted by frequency shifting at the rate of 10 bits per second. The total broadcast was less than three minutes.

The cardinality of 1679 was chosen because it is a semiprime. It can be arranged as a rectangle of 73 rows by 23 columns. The other arrangement, 23 rows by 73 columns, does not produce a meaningful result. The message forms the image shown on the right, or its inverse, when translated into graphics characters and spaces.

In 2009 the band Boxcutter made an album called the Arecibo Message, which has a lot of short songs.

Message as binary string

The message as a binary string is included below. Note that the choice of 1 representing higher frequency and 0 representing lower frequency is entirely arbitrary and the line breaks after every 23 bits are only included to allow for some ease in human readability.

Numbers

Part 1 — The numbers from 1 to 10

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, to be read from the top down. The bottom row contains markers which indicate the column from which the binary code for each number is intended to begin.

Even assuming that any extraterrestrial recipients would recognize binary, the encoding of the numbers may not be immediately obvious because of 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 their binary code has been distributed across an additional column next to the first (to the right in the image). This is intended to show that numbers too large to fit in a single column can be written in several contiguous ones (a scheme which is used elsewhere in the message). The additional columns are not marked by the least-significant-digit marker.

DNA elements

Part 2 — The elements constituting DNA

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, denoting the atomic numbers of hydrogen (H), carbon (C), nitrogen (N), oxygen (O), and phosphorus (P), the elements from which DNA is composed.

Nucleotides

Part 3 — The nucleotides of DNA
Deoxyribose
(C5H7O)		 Adenine
(C5H4N5)		 Thymine
(C5H5N2O2)		 Deoxyribose
(C5H7O)
Phosphate
(PO4)		 Phosphate
(PO4)
Deoxyribose
(C5H7O)		 Cytosine

(C4H4N3O)

 Guanine

(C5H4N5O)

 Deoxyribose
(C5H7O)
Phosphate
(PO4)		 Phosphate
(PO4)

The chemical groups from which the nucleotides of polymeric DNA sequences are built – the sugar deoxyribose, phosphate, and the four canonical nucleobases used in DNA – are then described as sequences of the five elements that appear on the preceding line. Each sequence represents the molecular formula of the chemical as it exists when incorporated into DNA (as opposed to the free form).

For example, the compound in the top left in the image is deoxyribose (C5H7O in DNA, C5H10O4 when free), whose formula 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.

It is displayed in this order because the DNA Elements in the previous section (Purple image as reference) describe hydrogen (H), carbon (C), nitrogen (N), oxygen (O), and phosphorus (P) in that order as well.

Double helix

Part 4 — The DNA double helix structure

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

11111111 11110111 11111011 01011110 (binary) [Using the double vertical columns above, read from top to bottom starting from the right column first, and then top to bottom from the left column.] = 4,294,441,822 (decimal)

A graphic of the approximate shape of the double helix in which double-stranded DNA polymers naturally exist; the vertical bar in the middle is a binary representation of the number of nucleotide base pairs in the human genome. The value depicted is around 4.3 billion, which was believed to be the case when the message was transmitted in 1974; it is now known that there are only approximately 3.2 billion base pairs in the human genome.

Humanity

Arecibo message part 5
Part 5 — Human form, the height and population of humans
 
  ʌ             X011011
  |              111111
  |              110111
X0111            111011
  |              111111
  v              110000

1110 (binary) = 14 (decimal)

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

The graphic in the center is a simple illustration of a human being. The element on the left (in the image) indicates the average height of an adult male in the US: 1.764 m (5 ft 9.4 in). This value is indicated by a horizontally written binary representation of the number 14, which is intended to be multiplied by the wavelength of the message (126 mm); 14 × 126 = 1,764 millimeters.

The element on the right of the image indicates the size of the global human population in 1974, approximately 4.3 billion (which, coincidentally, is within 0.1% of the number of DNA base pairs suggested for the size of the human genome earlier in the message). In this case, the number is oriented in the data horizontally rather than vertically. The least-significant-digit marker is in the upper left in the image, with bits going to the right and more significant digits below.

Planets

Part 6 — The Sun and the planets
                  Earth
Sun Mercury Venus       Mars Jupiter Saturn Uranus Neptune Pluto

A graphic depicting the Solar System, showing the Sun and nine planets in the order of their distance from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto (Pluto was reclassified in 2006 as a dwarf planet by the International Astronomical Union). 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. Additionally, the human figure is shown just above 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

Part 7 — The Arecibo radio telescope
bottom middle two rows shown in White as reference in the image:
     100101
<--- 111110X --->
100101 111110 (binary) = 2,430 (decimal)
AreciboMessageShifted
The Arecibo message as decoded into 23 rows and 73 columns. Although unintelligible, the message in this format appears sufficiently organized to show that it is not a random signal.

The last part is a graphic representing the Arecibo radio telescope and indicating its diameter with a binary representation of the number 2,430; multiplying by the wavelength of 126 mm gives 306.18 m (1,004 ft 6 in). In this case, the number is oriented horizontally, with the least-significant-digit marker to the lower right in the image.

The part of the image that resembles a letter "M" is there to demonstrate that the curved line is a concave curved mirror.

Arecibo Answer crop circle hoax

Chilbolton crop circle
The Arecibo reply was the name given to a crop circle that was made in the farmland next to the Chilbolton radio telescope in Hampshire, UK, on 19 August 2001. It was 75 feet wide and 120 feet long.

The "Hampshire pattern" or "Chilbolton Code formation" or "Arecibo answer" was a crop circle that appeared in 2001 near the Chilbolton radio telescope in Hampshire, UK, which echoed the visual representation and most of the information from the original Arecibo message with some significant differences including location/origin, DNA configuration, and appearance.

The SETI Institute Online rebutted the idea that this was a genuine extraterrestrial response, by saying, "This is highly improbable. There is no evidence to suggest an other-than-earthly origin for these graphics." The crop circle is a near replica of the Arecibo message, with the same 23 × 73 grid. Most of the chemical data remains the same, with the exception that in the section detailing important chemical elements, silicon has been added, and the diagram of DNA has been rewritten. At the bottom, the pictogram of a human is replaced with a figure with a large, bulbous head. A solar system with 9 planets is also depicted, with emphasis placed on the 3rd, 4th, and 5th planets of the system. The Arecibo telescope is replaced by a replica of a crop circle that appeared in the same field one year before, and the binary representation of the transmitter's diameter is altered.

See also

Kids robot.svg In Spanish: Mensaje de Arecibo para niños

  • Active SETI
  • Communication with extraterrestrial intelligence (CETI)
  • Cosmos, a 2019 science fiction film featuring a response to the Arecibo message
  • List of interstellar radio messages
  • METI (Messaging Extraterrestrial Intelligence) (organization)
  • Pioneer plaque
  • Voyager Golden Record
  • Wow! signal
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