The Arecibo Message
The account
Humanity sent its address to the stars, and a crop formation in a wheat field in 2001 would be the reply.
What investigators found
The message is real and is still traveling toward a cluster of stars. The "reply" in an English field is considered the work of humans.
The story
On November 16, 1974, the Arecibo radio telescope in Puerto Rico, then the largest in the world, beamed into space a message of 1,679 pulses, created by Frank Drake with help from Carl Sagan. Arranged on a grid, they form a picture showing the numbers 1 to 10, the DNA molecule, a human figure, the Solar System and the telescope itself.
The destination is the star cluster M13, about 25,000 light-years away. Any reply would take at least twice that long to arrive. In 2001, a design imitating the message appeared in a wheat field in England, and it was treated as a hoax. The Arecibo telescope collapsed in 2020, but the signal keeps traveling.