Behind the message sent to aliens 50 years ago

A bold call

A bold call, An impressive construction, Vision of connection, A team effort, 1. Numbers, 3. Nucleotides, 5. Humanity, 7. Telescope, A long distance, The dark side, Competing signals from Earth, Estimating first contact, Honoring the original, Collapse

The Arecibo Message was sent into the cosmos on November 16, 1974, from the Arecibo Observatory in Puerto Rico. It was nothing more than a brief stream of binary data, delivered as a long-distance “hello” to unknown cosmic neighbors.

An impressive construction

A bold call, An impressive construction, Vision of connection, A team effort, 1. Numbers, 3. Nucleotides, 5. Humanity, 7. Telescope, A long distance, The dark side, Competing signals from Earth, Estimating first contact, Honoring the original, Collapse

The gigantic bowl-shaped radio dish of the observatory was built in a natural sinkhole. The steel platform suspended above it weighed an astonishing 900 US tons (816 metric tons).

Vision of connection

A bold call, An impressive construction, Vision of connection, A team effort, 1. Numbers, 3. Nucleotides, 5. Humanity, 7. Telescope, A long distance, The dark side, Competing signals from Earth, Estimating first contact, Honoring the original, Collapse

Astronomer Frank Drake (renowned for the Drake Equation, which is used to estimate the number of extraterrestrial civilizations in the Milky Way Galaxy) designed the message that would be sent. His innovative approach framed humanity’s attempt to communicate with aliens in the simplest term: the binary code.

A team effort

A bold call, An impressive construction, Vision of connection, A team effort, 1. Numbers, 3. Nucleotides, 5. Humanity, 7. Telescope, A long distance, The dark side, Competing signals from Earth, Estimating first contact, Honoring the original, Collapse

Graduate students at Cornell University helped refine Drake’s design, contributing key elements to the message that would inevitably be sent.

Format

A bold call, An impressive construction, Vision of connection, A team effort, 1. Numbers, 3. Nucleotides, 5. Humanity, 7. Telescope, A long distance, The dark side, Competing signals from Earth, Estimating first contact, Honoring the original, Collapse

The final message contained 1,679 bits (short for “binary digits”) arranged in a grid of 73 rows by 23 columns. The message consists of seven parts that encode various pieces of information about humanity.

1. Numbers

A bold call, An impressive construction, Vision of connection, A team effort, 1. Numbers, 3. Nucleotides, 5. Humanity, 7. Telescope, A long distance, The dark side, Competing signals from Earth, Estimating first contact, Honoring the original, Collapse

The first section of the Arecibo Message lists the numbers from one to 10 in binary. This serves as a foundation for the message, demonstrating to aliens the concept of counting and binary representation, which should be intelligible to other advanced beings.

3. Nucleotides

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The third part outlines the chemical formulas of 12 organic molecules (or “nucleotides”) that make up DNA. All of Earth's life forms are constructed using the same genetic framework, and this section shows what that framework looks like using atomic numbers of elements.

5. Humanity

A bold call, An impressive construction, Vision of connection, A team effort, 1. Numbers, 3. Nucleotides, 5. Humanity, 7. Telescope, A long distance, The dark side, Competing signals from Earth, Estimating first contact, Honoring the original, Collapse

A human figure stands at the center of this section, accompanied by a vertical line on the left to indicate the average height of humans (about 5'9", or 175 cm, encoded using the wavelength of the transmission). On the right, the Earth's human population (approximately 4.3 billion in 1974) is encoded in binary.

7. Telescope

A bold call, An impressive construction, Vision of connection, A team effort, 1. Numbers, 3. Nucleotides, 5. Humanity, 7. Telescope, A long distance, The dark side, Competing signals from Earth, Estimating first contact, Honoring the original, Collapse

The final section displays the Arecibo radio telescope as the transmission source. Its shape is depicted in binary alongside its approximate diameter of 1,004 ft (306 meters). The letter “M” was put there to show that the curved line is a concave mirror.

A long distance

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The encoded transmission was sent in the direction of Messier 13, a massive star cluster in the Hercules constellation some 25,000 light-years away.

The dark side

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Critics have warned that broadcasting Earth’s location could invite danger. Criticisms such as these have been known to draw on speculative theories like the Dark Forest, where civilizations hide to avoid attracting hostile forces.

Competing signals from Earth

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While the Arecibo Message was deliberate, Earth continuously leaks signals into space via TV broadcasts and radio waves. These emissions make our existence detectable to any advanced alien listeners.

Estimating first contact

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Scientists estimate that four stars will receive the Arecibo Message within its first 500 years of travel, starting with a star known as Gaia DR3 1328057940089589376, located approximately 395 light-years away.

Honoring the original

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The new design echoed the 1974 version, sticking to binary code and schematic simplicity while modernizing details like excluding Pluto and adding key cosmic landmarks like Saturn’s rings. Interestingly, the biological data of life on Earth was omitted.

Collapse

A bold call, An impressive construction, Vision of connection, A team effort, 1. Numbers, 3. Nucleotides, 5. Humanity, 7. Telescope, A long distance, The dark side, Competing signals from Earth, Estimating first contact, Honoring the original, Collapse

In 2020, the Arecibo Observatory collapsed due to structural damage caused by Hurricane Maria. Its loss marked the end of an era for radio astronomy and interstellar communication.

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