On this day in 1974, the most powerful broadcast ever deliberately beamed into space was made from Puerto Rico.
So what’s all the fuss about the Arecibo message? Here’s everything you need to know:
What is the Arecibo message?
The Arecibo message is a three-minute transmission of exactly 1,679 binary digits carrying basic information about humanity in the hopes that it might reach extra-terrestrial beings.
It was first broadcast into space on November 15 1974, aimed at the globular star cluster M13.
This cluster is located near the edge of the Milky War - approximately 21,000 light years away from us - and contains approximately a third of a million stars.
Since the message was sent all those years ago, it's travelled just 259 trillion miles - a small feat considering its journey will take around 25,000 years to complete.
Who created the Arecibo message?
The Arecibo message was the brainchild of Dr Frank Drake, Carl Sagan and other prominent scientists and mathematicians.
What does the message say?
It doesn't technically say anything but is meant to depict human life through a series of graphics.
The message includes graphics of the Arecibo telescope, our solar system, our DNA, a stick figure of a human and some of the biochemicals of earthly life.
According to the Search for Extraterrestrial Intelligence Institute (SETI), a scientific organisation that researches extraterrestrial life, says it's unlikely we'll ever get a reply.
However, it said, "the experiment was useful in getting us to think about the difficulties of communicating across space, time and a presumably large culture gap."
