Hundreds of messages are being sent to a planet located 20 light-years from Earth in the hope that it will be received by intelligent life.
Some 500 photographs, drawings and text messages are being transmitted by a giant radio telescope located in Ukraine which is normally used to locate and track the asteroid.
The planet was chosen because it has features that make it capable of having life on its surface.
Any reply to messages, collected by a social website called Bebo, can not reach Earth until within 40 years.
The competition called "A Message from Earth" invited twelve million visitors to original send missives to be received by extraterrestrial life.
The topics ranged from environmental, political, world peace, to family relationships.
After being translated into binary language, the 500 selected messages are being sent to about 120 trillion miles away in space via radio waves the telescope-radar Space Agency of Ukraine, located in Evpatoria.
"We are here"
The communication is being transmitted from the morning of Friday to reach the moon in just 1.7 seconds and taking less than seven hours to leave the solar system.
Organizers hope that the package of messages to reach its target, the planet Cliese 581C, at the beginning of the year 2029.
The spokesman for the website Bebo, Mark Charkin, said: "A message from Earth is an opportunity for the inhabitants of digital today .... to reconnect with the science and outer space in a simple, fun and profound way."
Seth Shostak, an astronomer at the Institute of Search for Extraterrestrial Intelligence in California said the point of this initiative is not whether the alien may or may not receive the message.
"The point is simple: we are here and we are smart enough to build a radio transmitter," said the scientist at the BBC. "If there is someone there and find the signal, at least they will know that," she said.