Aliens may have tried to contact humans for the first time with a mystery radio signal transmitted from deep in space.
Listening posts picked up the strong signal in May and since then scientists have tried to decode the transmission.
Russian astronomers were the first to hear the noise from the direction of a star called HD 164595, almost 100 light years away from Earth.
They revealed their findings to other teams of scientists, but they have failed to agree whether the signal is a bid to send a message or just space noise.
To try and put a fix on the source and to catch any future messages, the Russian team want to establish a permanent listening post to monitor any other activity from the same location.
Search for extra-terrestrials
They hope to intercept other transmissions for analysis to see if they are generated by extra-terrestrial life or simply background noise from the universe, such as solar flares or stray signals from Earth reflected back.
Analysis will also place the signal on the Kardashev Scale – type 1 civilisations such as Earth can conserve and use energy from nearby stars, like Earth; type 2 can harness all the energy of their sun, while type 3 control the power generated by their universe.
The astronomers can categorise the signal from the wavelength and strength of the transmission.
No signals from extra-terrestrial life forms have been proven as such by scientists.
Two deep space searches are underway – one to detect habitable planets which may support life and another to identify the existence of extra-terrestrials.
Sophisticate life form
The Search for Extra-Terrestrial Intelligence (SETI) says the signal emanates from a planet circling a star in the Hercules star system.
If the transmission is from aliens, they would be far more sophisticated than life on Earth, explained SETI scientists.
However, they are sceptical about the origin until further investigations are completed as an ice planet similar in size and composition to Neptune.
If aliens live in the distant system, they are not expected on Earth any time soon. A space craft from HD 164595 would have to travel an estimated 580 trillion miles to reach the solar system.