Skip to content
TrackPodcasts
scienceNov 27, 20251:55pending

# The Arecibo Message: Humanity's Cosmic Hello to the Stars

About this episode

# This is your Astronomy Tonight podcast.

Good evening, stargazers! Today is November 27th, and we're celebrating one of the most mind-bending discoveries in the history of astronomy!

On this date in 1974, humanity received the most famous cosmic "hello" ever transmitted through the universe. Astronomers working at the Arecibo Observatory in Puerto Rico beamed the iconic **Arecibo Message** toward the globular star cluster M13, located about 25,000 light-years away.

Now, here's where it gets absolutely wild: This wasn't just any radio signal. The message was a carefully crafted binary transmission containing information about humanity, our solar system, and our DNA structure. Scientists encoded it in a 1,679-bit transmission—a deliberately prime number to hint at intelligent organization—which can be arranged into a 73 by 23-pixel image. When decoded, it shows the numbers 1-10, atomic numbers of essential elements, a DNA double helix, a human figure with a height reference, our solar system, and the Arecibo telescope itself!

But here's the cosmic joke: by the time that message reaches M13 in about 25,000 years, if anyone's listening, humanity might have completely reinvented itself or moved on to colonize distant worlds. We basically sent a cosmic message in a bottle, hoping someone checks their mail in the year 27,000!

---

If you've enjoyed learning about this fascinating moment in astronomical history, please **subscribe to the Astronomy Tonight podcast**! For more information about today's astronomical event and other cosmic wonders, be sure to check out **Quiet Please dot AI**. Thank you for listening to another Quiet Please Production!

This content was created in partnership and with the help of Artificial Intelligence AI

This episode includes AI-generated content.

Get every episode summarized

Each time Astronomy Tonight publishes, we email you a written briefing from the transcript — the topics, who appeared, and any specific claims, with the ad reads skipped.

Email me new episodes

Free for 3 shows. No card needed.

Hosts & guests

No transcript yet

This episode has not been transcribed. Request it and it moves to the front of the queue.

# The Arecibo Message: Humanity's Cosmic Hello to the Stars

Astronomy Tonight

0:00
1:55

More episodes

More from Astronomy Tonight

View all episodes →