Space Science · Lesson 05 · 1974

The Arecibo Message

In 1974, humanity aimed the world's largest radio telescope at a star cluster 25,000 light-years away and broadcast a binary message. Can you decode what we said?

Message Decoder

Interactive
10×

Click or hover any region to identify it

Hover over the message to explore
Each colored section encodes a different fact about life on Earth.

Binary Primer

How it works

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: 23 columns × 73 rows.

DecimalBinaryDecimalBinary
116110
2107111
31181000
410091001
5101101010