Arecibo message meaning
The Arecibo message was sent on 16 November 1974 from the Arecibo telescope. It is 1,679 bits, and 1,679 is 23 times 73, so the bits can be arranged as a picture. Frank Drake designed it. The broadcast was aimed at the globular cluster M13. It is a demonstration as much as a letter.
1,679 bits, sent once, toward a cluster of stars.
The name. Arecibo is the observatory in Puerto Rico whose transmitter sent the message. The name is a place. The message is a grid. People say “the Arecibo signal” and mean this broadcast. It is not a signal we heard. It is one we made.
Where it comes from
The ceremony on 16 November 1974 marked an upgrade of the Arecibo radio telescope. Frank Drake, who had written the form of a scientific search for other transmitters, used the new transmitter to send a picture. The length was chosen because 1,679 is the product of two primes, 23 and 73. A reader who tries both arrangements and keeps the one that is not noise will get 73 rows of 23 columns. Read in that grid, the bands are: the numbers one through ten in binary; the atomic numbers of hydrogen, carbon, nitrogen, oxygen, and phosphorus; the formulas of the sugars and bases in DNA; a sketch of the double helix; a human figure with a measure of height and the population of the earth; a map of the solar system, with Earth displaced to show it is the source; and a drawing of the telescope itself, with its diameter. The target was M13, a dense cluster. The cluster will have moved by the time the light arrives, tens of thousands of years from now. Drake was clear that the sending was also a way to show what the transmitter could do. A message can be real and still be a ceremony. The lexicon draws a grid schematic, not a bitmap copy of the famous image, so the page explains the bands without pretending to republish the pixels as a relic.
Modern
Primes as a frame
Binary is the ink. The primes are the frame. Without 23 and 73, a string of 1,679 bits is a line. With them, it is a picture, if you guess the orientation. That guess is the kind of guess the designers thought a technical reader would make. It is not a code in the sense of a secret. It is a compression that assumes curiosity and arithmetic. Leibniz’s binary arithmetic is the ancestor of the ink. The 1974 broadcast is a use of it. The power symbol is a different use of 1 and 0, on a button, not in a sky.
Modern
One transmission
The message was not repeated as a program of contact. It was sent. The telescope’s later life, including its collapse in 2020, is the history of a building. It does not multiply the message into a correspondence. No answer has been attributed to it. Filing it with the Wow! signal is a convenience for readers. The Wow! signal is something a different telescope wrote down in 1977. Arecibo is something we shouted in 1974. Direction is the difference.
In popular culture
internet · 2001
The Chilbolton 'Arecibo answer' crop formation
A crop formation beside the Chilbolton radio telescope reproduced the 23×73 grid with altered elements, DNA, a big-headed figure and a different telescope; believers called it a reply, SETI called an alien origin highly improbable.
The most famous 'response' was made in a Hampshire field.
Sourcefilm · 2019
Cosmos (film)
The British film is listed among pictures that stage a response to the message.
The British film is listed among pictures that stage a response to the message, which is a later reading of the mark.
SourceWorth knowing
- The familiar coloured picture is an illustration; the 1974 binary transmission carried no colour. Source
Questions
What does the Arecibo message mean?
The Arecibo message was sent on 16 November 1974 from the Arecibo telescope. It is 1,679 bits, and 1,679 is 23 times 73, so the bits can be arranged as a picture. Frank Drake designed it. The broadcast was aimed at the globular cluster M13. It is a demonstration as much as a letter.
Where does the Arecibo message come from?
The ceremony on 16 November 1974 marked an upgrade of the Arecibo radio telescope. Frank Drake, who had written the form of a scientific search for other transmitters, used the new transmitter to send a picture.
Why does Cosmos use Arecibo message?
The British film is listed among pictures that stage a response to the message. The British film is listed among pictures that stage a response to the message, which is a later reading of the mark.
Near this
- BinaryTwo digits. Every later machine script is a reader of them.
- Pioneer plaqueA metal card bolted to a machine, written for a reader who is not from here.
- Hydrogen lineA spin-flip of the smallest atom, used as a ruler for strangers.
- Voyager Golden Record coverInstructions for a disc: how to play it, and where the player lives.
Sources
Named when the entry depends on a text, a date, or a standard. Catalog numbers are not invented.
Your margin
Private. It stays in this browser and never joins the canon.
symbol.wiki, edited as Sigilla. Last reviewed 20 October 2026. A reading of public tradition, not a ruling.