More than 25,000 messages have been transmitted into outer space in a bid to reach a distant planet that may hold life.
But don't hold your breath for an immediate response as it will take four decades for a reply to reach Earth and that's only if the messages are received by intelligent life that understand them.
The messages, transmitted at about midday AEST from the Tidbinbilla Deep Space Communication Complex outside Canberra, have come from 195 countries including some from places such as the Vatican city, Antarctica and Kosovo.
Each message, a maximum of 160 characters long, was collated on a website called "Friends from Earth" and all 25,880 messages were beamed together in a giant twitter-like message that took two hours to send.
Their target is the nearest Earth-like planet outside our solar system, called Gliese 581d, which is 20.3 light years away.
Traveling at the speed of light, or 300,000km per second, it will take 20.3 years for the messages to reach the planet and just as long for a response back to Earth.
The antenna used to transit was beaming to 302 gigawatts or the equivalent energy of 302 billion mobile phones or every person on earth sending 50 texts at one time.
Scientists believe that as Gliese 581d is four planets away from its own sun, also named Gliese 581, the conditions make it possible to contain life.
"People are really excited about Gliese 581d because they think it might have life," Hello from Earth project manager Wilson da Silva told the gathering in Canberra moments before the transmission.
"We don't actually know if there's life on Gliese 581d ... but what we do know is that it has the conditions for life, we don't know that it has a technical civilisation that could actually receive the signal we're transmitting."
Mr Da Silva said while some of the messages were considered inappropriate to send, others were heartfelt, like that from Aboriginal astronomer Yidumduma Bill Harney from the Wardaman people near Katherine, which read "Our dream, we're telling to them young kids. We're talking all this dream for the future."
Indigenous school children from the Karalundi Aboriginal Education Community School in Meekatharra, WA, led the countdown moments before the messages were beamed into space.
However, almost as if it was straight out of a Star Trek movie, their counting was interrupted by an announcement from the station's control room.
"Can I have your attention please, (we are about to) ... commence transmission to Gliese 581-delta with a very special hello from Earth," the male American voice said.
The project was a part of National Science Week, which in its 12th year aims to create an awareness of the importance of science and encourages students to pursue a science career.