'Alien' signal likely isn't, but if it is, they're way smarter than us - CNET

"The most likely explanation for the signal from the direction of HD 164595 is that it's *not* a sign of extraterrestrial intelligence," METI (for Messaging Extra-Terrestrial Intelligence) Inteational President Doug Vakoch told me via email. "It could be due to a satellite flying overhead at just the right time, or it could be radio interference caused by an Earth-based transmitter. But there could also be a natural explanation that we haven't yet figured out."

This latest excitement over weird things happening beyond our solar system comes less than a year after talk started about possible alien megastructures around the star KIC 8462852 and with talk still swirling about Proxima b, a potentially habitable planet orbiting the closest star to the sun.

Proxima b, the closest Earth-like exoplanet,...

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Regardless of how low the odds are that the mysterious signal will tu out to be aliens, both organizations have already gone to work to take a closer look and listen to HD 164595.

When I last checked with Shostak, on Monday, the SETI Institute had already pointed the Allen Telescope Array in northe Califoia at the star and picked up nothing in its early observations. The ATA has yet to cover the full range of frequencies in which the signal could be detected, though, something Shostak says will continue over the next day or two.

The Panama-based telescope that METI Inteational uses for such searches has been plagued by bad weather hampering its ability to check things out, but Vakoch is hopeful the weather will clear up Tuesday night.

Probability aside, what if the signal were to be confirmed as alien? If an advanced civilization really is sending signals into space, what might that society be like?

In a word, it would probably be pretty impressive to our eyes.

If a civilization in the vicinity of HD 164595 were sending such a strong signal every which way in space, it would have to be what's classified as a Type II civilization on the Kardashev scale, which means the society would have the technical capability to tu a star into its personal power plant.

"If the signal from HD 164595 is from a civilization that is radiating out electromagnetic signals in all directions, that takes tremendous energy -- the energy of an entire star, represented by a Type II civilization," Vakoch told me.

To be clear, this doesn't mean being able to haess all the energy of a star that hits a single planet by, say, blanketing the atmosphere with transparent solar panels -- that capability would constitute a Type I civilization. Instead it means haessing all of a star's power that radiates in all directions, perhaps by building a hollow shell called a Dyson sphere around the star itself.

A society with that capability seems like one we wouldn't want to upset.

Another possibility is that a distant civilization could be narrowly targeting a signal only in our direction, which would take less power, but still more than humans would be able to muster right now. Vakoch estimates that a Type I civilization might be able to send out such a transmission.