Scientists in Russia have detected a radio signal, possibly transmitted by a star system 94 light-years away, sparking speculation that this may be an attempt by intelligent extraterrestrial life to contact our solar system.
HD 164595, a system few billion years older than the Sun but centred on a star of comparable size and brightness, is the purported source of a signal found with the RATAN-600 radio telescope in Russia.
This system is known to have one planet, a Neptune-sized world in a very tight orbit, making it unattractive for life. However, there could be other planets in this system that are still undiscovered.
Scientists speculate that the transmission could be from a technically proficient society.
The patch of sky from which the signal seems to be coming agrees in the east-west direction with HD 164695's coordinates, researchers said.
However, this does not necessarily mean that it comes from the same star system.
The observations were made with a receiver having a bandwidth of 1 GHz. That 200 times wider than a television signal, and billion times wider than the bandwidths traditionally used for Search For Extraterrestrial Intelligence.
"We can work backwards from the strength of the received signal to calculate how powerful an alien transmitter anywhere near HD 164595 would have to be," said Seth Shostak, Senior Astronomer at SETI Institute in the US.
Shostak said there could be two scenarios. The alien transmitter may have broadcast in all directions. Then the required power would be 100 billion billion watts.
"That is hundreds of times more energy than all the sunlight falling on Earth, and would obviously require power sources far beyond any we have," he said.
The second possibility could be that the alien transmitter may have aimed their transmission at our solar system.
This would reduce the power requirement, but even if they are using an antenna the size of the 1000-foot Arecibo instrument, they would still need to wield more than a trillion watts, which is comparable to the total energy consumption of all humankind, researchers said.
"Both scenarios require an effort far, far beyond what we ourselves could do, and it is hard to understand why anyone would want to target our solar system with a strong signal," said Shostak.
"This star system is so far away they won't have yet picked up any TV or radar that would tell them that we're here," he said.
The chance that this is a signal from extraterrestrials is not very promising, and scientists doubt that they have found alien life.