Aliens could contact Earth imminently.
Space boffins are nervously waiting for extraterrestrials to respond to a message that was beamed into the sky 40 years ago - with 10pm on Tuesday (22.08.23) the earliest point that they could receive an answer.
Two Japanese astronomers, Masaki Morimoto and Hisashi Hirabayashi, sent their message out on August 15, 1983 by blasting 13 drawings in radio waveform to the Altair star 16.7 light years away.
Images sent included a history of life on Earth, what humans look like and an explanation of DNA.
The experts have deployed the Japan Aerospace Exploration Agency's antenna as they search for a reply from the little green men.
Hirabayashi said: "I believe in aliens but they are very difficult to find."
Morimoto added: "Altair may have a planet whose environment can sustain life."