A radio signal emanating from a star 95 light-years away had the internet buzzin’ about the possibility of extraterrestrials trying to talk to us. Maybe we really had stumbled on aliens!

As it turned out, we should have taken a chill pill (or five) and calmed down a bit. SETI researchers following up on the signal and the star, HD164595 and, trying to make sense of what exactly is going on, learned that — whoops — it was, um, just us.

All this talk of intelligent lifeforms from another world has once again drawn attention to something called the Kardashev scale, a method of categorizing the technological progress of an intelligent civilization. Thank Russian astronomer Nikolai Kardashev, who in 1964 created the spectrum that gauges a species’ ability to harness energy and communicate with whomever else lingers in the universe.

There are three types of Kardashev civilizations:

  • Type I: a civilization that can utilize and store all available energy produced by a nearby star. Humans are not quite a Type I civilization yet (we’re probably a Type 0), but we’re on our way. We receive sunlight from the sun, and turn it into a usable energy to help us build cities and make dank memes and whatnot. As we get better at harnessing that energy, we would presumably be capable of controlling most or all other natural forces that guide the planet’s processes. For example, we might be able to control the weather artificially, or halt or speed up seismic processes at will. Theoretical physicist Michio Kaku predicts humans will become a Type I civilization within the next couple of centuries. Modern estimates peg energy consumption to somewhere between 4 x 10^16 and 4 x 10^17 watts.
  • Type II: when a civilization can harness the energy of the entire star it’s orbiting and transfer it to the planet or another vast technological structure. The most classic example of how this would work is the Dyson sphere — a megastructure which would basically cover a star from pole to pole and capture all its energy to siphon back to the planet. Having this kind of energy would basically make a species impervious to extinction by external cosmic threats, like a doomsday asteroid that could now be vaporized by a laser beam. Modern estimates peg energy consumption to the average luminosity of the sun — so about 4 × 10^26 watts.
  • Type III: a civilization that captures and controls the entire energy of its host galaxy. We’re talking about a species so advanced it has taken over billions of star systems own its own and turned each of those stars into individual power plants. Interstellar travel has become kid’s play. Maybe these aliens aren’t even made of flesh and blood — maybe they’re actually cyborgs. Energy consumption would round off to something like 4 × 10^37 watts.

This might seem like an arbitrary scale, but it’s a useful way for SETI researchers to imagine what exactly they might be observing if we ever do come across signs of extraterrestrials attempting to communicate with us.

Remember Tabby’s Star, which sparked a bunch of weird theories that aliens had built an incredible megastructure in its orbit? It’s almost probably not aliens causing the strange activity astronomers are observing in the vicinity, but if it were, that civilization would be a Type II civilization — advanced enough to construct an orbital array of infrastructure capable, powered exclusively by a star.

When it comes to HD164595, the new signal — if it had artificial origins — would suggest the presence of a Type I or Type II civilization in the region. The signals strength suggests something really powerful produced it, like an isotropic beacon (a hypothetical device that could emit a radio signal in all directions, presumably for the express purpose of communicating with other species in the universe.)

Douglas Vakoch, the president of METI International (which is currently using Panama’s Boquete Optical Observatory to further investigate the star in question), tells Inverse:

“What those Type I and Type II civilization classes mean is, if in fact there’s an extraterrestrial civilization transmitting from 94 light-years away, if it’s being transmitted in all directions, so omnidirectional, it would be coming from a civilization that’s advanced enough to have created a Dyson’s sphere, so it would be a Type II. If it’s focused at Earth, then the civilization doesn’t need to have quite that great of a capability. It could be a Type I.”

Basically, if the signal really is from aliens, the type of intelligent life we’re dealing with depends on whether or not they were trying to phone Earth specifically, or cast out a general signal out to everyone. If it’s the former, the aliens are probably not much more advanced than us, but were smart enough to have reason to believe the solar system had the potential to house life. If it’s the latter, then we’re dealing with aliens that are exponentially more advanced than us.

Which means if they’re hostile, we’re screwed.

Photos via Kevin Gill

Neel is a science and tech journalist from New York City, reporting on everything from brain-eating amoebas to space lasers used to zap debris out of orbit, for places like Popular Science and WIRED. He's addicted to black coffee, old pinball machines, and terrible dive bars.