Space Science · Lesson 05 · SETI
From binary messages beamed at star clusters to golden records hurtling through interstellar space — five stories of humanity reaching out to the cosmos.
Click or hover any region to identify it
The message contains only 1679 bits — each either a 1 (transmitted pulse) or a 0 (silence). To read it, you must arrange those bits into a rectangle. Only one arrangement makes an image, conventionally described as 73 rows × 23 columns.
| Decimal | Binary | Decimal | Binary |
|---|---|---|---|
| 1 | 1 | 6 | 110 |
| 2 | 10 | 7 | 111 |
| 3 | 11 | 8 | 1000 |
| 4 | 100 | 9 | 1001 |
| 5 | 101 | 10 | 1010 |
Hover over bars to see intensity values
The chart above shows a recreation of the signal data recorded by Big Ear. The red spike represents the famous 6EQUJ5 sequence — a signal 30 times stronger than background noise, lasting 72 seconds. It matched the expected signature of an interstellar signal at the hydrogen frequency (1420 MHz).
Big Ear used an alphanumeric system to record signal intensity. Digits 0–9 represent intensities 0–9, and letters A–Z represent 10–35. Each character maps to one intensity level:
| Character | Intensity | Character | Intensity |
|---|---|---|---|
| 6 | 6 | U | 30 |
| E | 14 | J | 19 |
| Q | 26 | 5 | 5 |
The Voyager Golden Record is a phonograph record included aboard both Voyager spacecraft, launched in 1977. It carries sounds and images selected to portray the diversity of life and culture on Earth — intended as a message to any intelligent extraterrestrial life form who might find it. The record's cover includes instructions, in symbolic language, explaining how to play it.
Johnny B. Goode
Chuck Berry
Represents the energy and invention of rock and roll. Sagan fought to include it despite objections that rock was "adolescent," arguing that aliens would appreciate its driving, mathematical rhythm and pure joy.
Dark Was the Night, Cold Was the Ground
Blind Willie Johnson
A haunting, wordless blues slide-guitar piece expressing profound human loneliness. The committee chose it specifically to represent the universal human experience of sorrow and isolation.
The Well-Tempered Clavier, Book 2
Johann Sebastian Bach
Bach's compositions are renowned for their strict mathematical precision, symmetry, and counterpoint—qualities scientists hoped advanced extraterrestrial minds would readily recognize and appreciate.
Symphony No. 5, First Movement
Ludwig van Beethoven
With its iconic four-note opening motif, this masterpiece captures the dramatic, monumental scale of human struggle, resilience, and triumph.
Navajo Night Chant
Traditional Navajo
Chosen to represent the rich spiritual and healing traditions of Indigenous North Americans, capturing the resonant depth of the human voice in ceremonial prayer.
Morning Star and Devil Bird
Australian Aborigine
An ancient vocal and didgeridoo recording that acts as a deep-time capsule, showcasing the musical heritage of one of the oldest continuous living cultures on Earth.
In the summer of 1950, physicist Enrico Fermi was having lunch with colleagues at Los Alamos National Laboratory. The conversation turned to flying saucers and the probability of extraterrestrial life. After some discussion, Fermi suddenly asked: “Where is everybody?”
His question cut to the heart of a deep contradiction. The Milky Way is roughly 13.6 billion years old. It contains an estimated 100–400 billion stars, many with planets. If even a tiny fraction of those planets developed intelligent life, and even a tiny fraction of those civilizations developed interstellar travel, the galaxy should be teeming with evidence of their existence.
Yet we see nothing. No signals. No megastructures. No visitors. No artifacts. The universe appears extraordinarily, suspiciously silent.
This contradiction — the apparent conflict between the high probability of extraterrestrial civilizations and the total lack of evidence for them — is known as the Fermi Paradox.