The Message We Sent Into the Dark
September 5, 2026 · by White Nights
On November 16, 1974, Carl Sagan and Frank Drake stood at the Arecibo Observatory in Puerto Rico and sent a message into space. It was 1,679 bits long, took three minutes to transmit, and was aimed at a globular cluster called M13 — a dense collection of roughly 300,000 stars, about 25,000 light-years from Earth.
The message was designed to be decoded by any intelligence capable of receiving it. It contained the numbers one through ten in binary, the atomic numbers of the elements in DNA, a diagram of the DNA double helix, a figure of a human being with their height encoded alongside, the population of Earth at the time, a diagram of our solar system, and a schematic of the Arecibo telescope itself. All of it packed into a grid 73 rows by 23 columns, chosen because both numbers are prime.
M13 will not receive the message for another 25,000 years. And even if something there does receive it and reply, we won't hear back for 50,000 years after that. Sagan understood this. He always said the message was less about expecting a reply and more about the act itself — about a species choosing, for the first time, to announce its presence to the universe.
Drake had done the arithmetic years earlier. He had written an equation to estimate the number of civilisations in the galaxy capable of communication. It's called the Drake Equation, and it's less a calculation than a framework for holding uncertainty — a way of being precise about how much we don't know.
The Arecibo telescope itself was damaged by Hurricane Maria in 2017 and collapsed in 2020. The message it sent is still travelling.