Daily Archives: March 13th, 2008

Was this a response to the 1974 Arecibo Broadcast?

From abovetopsecret.com:

Was This A Message From Extraterrestrials??

Arecibo Radio Telescope, Puerto Rico
Pic: NAIC

Since a number of years, I have been pretty intrigued by the famous ‘reply’ to the Arecibo message. Though it has been mentioned in passing earlier here on ATS, but it hasn’t received the attention I thought it deserves.

That said, in 1974, a powerful broadcast was beamed into space from the Arecibo Radio Telescope, Puerto Rico. The transmission consisted of a simple pictorial message aimed at the globular star cluster M13. This cluster is roughly 21,000 light-years from us, near the edge of the Milky Way galaxy, and contains approximately a third of a million stars.

This was a very powerful emission, equivalent to a 20 trillion watt omni directional broadcast using Arecibo’s megawatt transmitter attached to its 305 meter antenna, concentrating the beam in a very narrow funnel of the sky. The emission, that could be detectable just about anywhere in the galaxy within that funnel, would have been detectable by a receiver similar in size to Arecibo’s. This transmission was the strongest man-made signal ever sent.


The message consisted of 1679 bits, arranged into 73 lines of 23 characters per line. The “ones” and “zeroes” were transmitted by frequency shifting at the rate of 10 bits per second and was transmitted at a frequency of 2380 MHz and modulated by shifting the frequency by 10 Hz. The total broadcast was less than three minutes.

This was the pictorial message sent…

As the author notes, the above is the original message sent in 1974. It’s a pretty straight forward, short and to the point message.