What could be an alien signal from a star system ninety-four light-years from Earth has been detected by Russian astronomers. Scientists, amateur astronomers and lay people across the world have again become super excited at the prospect of making contact with an advanced extraterrestrial civilization.
The source of the mysterious signal – HD 164595 – is a solar system that is just a few billion years older than ours, but is centered on a star of similar size and brightness to our Sun. The RATAN-600 radio telescope, a 576 m diameter circle of rectangular radio reflectors in Zelenchukskaya, at the northern foot of the Caucasus Mountains, picked up the signal.
HD 164595 is known to have a Neptune-sized planet, seventeen times the mass of the Earth, in a very tight orbit. According to Seth Shostak, Senior Astronomer at the SETI Institute in Mountain View, California, its orbit is too tight for there to be any chance of life as we know it.
Has this Russian radio telescope detected a signal from an advanced extraterrestrial civilization? Why did the discoverers wait fifteen months before telling the global scientific community about it? (Image: seti.org. Credit: nat-geo.ru)
That does not mean there might not be other planets in the system that we do not know of, he added.
Alien signal discussed last week
The signal has been discussed in a presentation given by a number of Russian scientists as well as Claudio Maccone, chair of the International Academy of Astronautics Permanent SETI Committee.
Dr. Maccone emailed SETI scientists with a description of the presentation, which he says included the signal believed to have come from the HD 164595 solar system.
Could the signal come from a technically-advanced civilization? Dr. Shostak says that at this time, we can only consider what is known so far.
We know of one Neptune-sized planet in the HD 164595 solar system. It orbits extremely close to its parent star, making it far too hot for life as we know it to exist. However, the system may have other exoplanets. (Image: adapted from allplanets.ru)
How sure can we be that this signal came from HD 164595, he wonders. The RATAN-600 radio telescope is of an unusual design and has a unique ‘beam shape’. The signal had a wavelength of 2.7 cm, which is equivalent to an 11 GHz frequency, giving it a beam of about 20 arcse by 2 arcmin – it’s a highly elongated patch in the north-south direction. RATAN-600 had an unusual beam shape.
The patch from which this signal appears to be coming from agrees in the east-west direction – the narrow part of the beam – with the sky coordinates of HD 165695. That is the discoverers’ basis for HD 165695 being the source of the signal. However, we cannot be certain that it came from there, Dr. Shostak pointed out.
The signal’s characteristics
A receiver with a bandwidth of 1 GHz made the observations. That is one billion times wider than the bandwidths the SETI Institute traditionally uses, and is two-hundred times wider than a TV signal. The strength was very weak – just 0.75 Janskys. Was this signal weak only because of HD 164595’s distance?
Maybe the very wide bandwidth of the Russian radio telescope diluted the signal, Dr. Shostak suggests. “Just as a pot pie, incorporating lots of ingredients, can make guessing the individual foodstuffs more difficult, a wide-bandwidth receiver can dilute the strength of relatively strong narrow-band signals,” he explained.
Power required for alien signal
Scientists can work backwards from the strength of this signal to calculate how powerful an extraterrestrial transmitter in or near HD 164595’s vicinity would have to be. One of two things may have occurred:
– The aliens decided to broadcast in all directions. To do this they would need 1020 watts, i.e. 100 billion billion watts. That is the equivalent of all the sunlight that falls on Earth multiplied by several hundred. Their power sources would be far beyond any we have.
– They pointed the transmission in our direction, which would require less power. However, even if they used an antenna the size of our 1000 foot Arecibo instrument, they would still need to be able to produce over one trillion watts, which would be the equivalent of all the energy we currently consume on Earth.
Seth Shostak, a senior astronomer at the SETI Institute, is also head of the International Academy of Astronautics’ SETI Permanent Committee. He says the chances that this signal came from smart aliens are small, but we cannot rule out the possibility. (Image: twitter.com/sethshostak)
Both possibilities would require an effort far beyond anything we are capable of. Why would any civilization out there want to target our solar system with such a strong signal?
HD 164595 is so far away – if an alien civilization exists there, they will not yet have picked up any radar or TV that would tell them we exist. Anything we receive from them now was sent 94 years ago, and at that time they would only have received stuff from Earth 188 years ago – in other words, nothing.
The Allen Telescope Array enters the scene
Dr. Shostak says the chance that this signal came from smart aliens is ‘not terribly promising’. Even the discoverers themselves do not sound too optimistic they have found ET. Even so, we should check out all reasonable candidates, given the importance of the subject.
— Jon Richards (@jrseti) 29 August 2016
Hence, the Allen Telescope Array (ATA), situated at the Hat Creek Radio Observatory in California, was swung in the direction of HD 164595 starting on August 28th. ATA scientists Gerry Harp and Jon Richards say that so far no signal has been picked up in that patch of the sky.
However, ATA has not yet covered the full range of possible frequencies. They plan to completely cover this big swath of radio dial over a two-day period. If they do pick up something, the SETI and radio astronomy communities would immediately be spurred to do more follow-up observations.
“We will continue to monitor this star system with the Array,” said Dr. Shostack.
Interesting theory here that an advanced civilization in HD 164595 could be specifically targeting us with a signal. https://t.co/9VzmkT9FmG
— Chad Richard Smalley (@chadrsmalley) 30 August 2016
Why did they wait so long?
This noteworthy discovery was made in May last year. The SETI community was not alerted by the discoverers until now, “which is not as expected”.
Whenever a signal appears to be of deliberate and extraterrestrial origin, one of the first things the discoverers do is to get others to try to confirm their observations. Why was this not done in this case?
Dr. Shostak concluded:
“So what’s the bottom line? Could it be another society sending a signal our way? Of course, that’s possible. However, there are many other plausible explanations for this claimed transmission – including terrestrial interference. Without a confirmation of this signal, we can only say that it’s “interesting.”
Video – An alien signal from far away?
In this Cosmos News video, a computer-activated voice explains that a strong spike in radio signals seemed to have come from the direction of a Sun-like star in the constellation Hercules, known as HD 164595. SETI researchers are currently attempting to determine exactly where it came from and what it is.