Sciency Words A to Z: METI

Welcome to a special A to Z Challenge edition of Sciency Words!  Sciency Words is an ongoing series here on Planet Pailly about the definitions and etymologies of science or science-related terms.  In today’s post, M is for:


In a sense, SETI researchers are just sitting by the phone waiting for somebody to call.  Maybe that’s the wrong way to go about it.  Maybe it’s time to pick up the phone, start dialing numbers, and see who picks up.

This idea is sometimes called active SETI, but it’s more common (and according to this paper, more appropriate) to use the term METI: the messaging of extraterrestrial intelligence.

Earth has been broadcasting TV and radio signals for over a century.  This has led to a common misconception that even now, aliens on some far off planet might be gathering around their equivalent of a television set, watching old episodes of Howdy Doody  or The Honeymooners.  Or perhaps, if the aliens live nearby, they’re currently listening to our more recent music.

But Humanity is only a Type 0 or Type I civilization, depending on which version of the Kardashev scale you’re using. Either way, our broadcasts are not actually that strong.  As David Grinspoon explains in his book Earth in Human Hands:

Our television signals are diffuse and not targeted at any star system.  It would take a huge antenna, much larger than anything we’ve built or planned, to pick up on them.  From a radio point of view our planet is not completely hidden, but it is hardly conspicuous.  This could easily change.  Targeted messages sent directly toward nearby stars would cause Earth suddenly to turn on like a spotlight, becoming an obvious beacon announcing, for better or worse, “We are here!”

Of course we’ve already done this.  Several times, in fact.  But not with enough consistency to truly make our presence known.

The first attempt was in 1974, when Frank Drake and Carl Sagan transmitted a message from the Arecibo radio telescope in Puerto Rico, aimed at the M13 globular cluster.  But according to Grinspoon, if aliens ever do pick up that signal, “[…] they might dismiss it as a momentary fluke.  We would.”  That’s because the Arecibo message was a quick, one-time thing.  By itself, it’s hardly proof beyond a reasonable doubt that life exists on Earth.

If we really want to get somebody’s attention, we have to send a sustained, repetitive signal, kind of like those repetitive radio pulses Jocelyn Bell detected in the 60’s.  We have the technology.  We can make METI a reality.  But should we?  Some say yes, others no.  After all, we have no idea who might hear our signal, or what form their response might take, and there is no guarantee that the aliens will be friendly.

METI is a discussion and a debate that maybe we all, as a species, should be part of.  Perhaps we should take a vote, because in the end, we all have a stake in what might happen.  And while we’re at it, there are some other issues we all, as a species, should vote on.  Or at least that’s what Grinspoon says we should do in his book.

Next time on Sciency Words A to Z, we’ll go back in time and check out the oceans of Mars.

Sciency Words A to Z: The Drake Equation

Welcome to a special A to Z Challenge edition of Sciency Words!  Sciency Words is an ongoing series here on Planet Pailly about the definitions and etymologies of science or science-related terms.  In today’s post, D is for:


In 1961, American astronomer Frank Drake proved that alien life exists.  He didn’t do this with a telescope or by analyzing a Martian meteorite. No, Frank Drake proved it with math, pure and simple.  Or at least that’s the impression some people seem to get when they first hear about the Drake equation.

The Drake equation was first presented in 1961 at a conference held at the Green Bank Telescope in West Virginia. Only ten people were in the audience when Drake gave his presentation (one of those ten people, by the way, was a young Carl Sagan).  And the topic to be discussed at this conference: a new and highly controversial idea called SETI.

In this article from Universe Today, Drake is quoted explaining what inspired his equation:

As I planned the meeting, I realized a few day[s] ahead of time we needed an agenda. And so I wrote down all the things you needed to know to predict how hard it’s going to be to detect extraterrestrial life.  And looking at them it became pretty evident that if you multiplied all these together, you got a number, N, which is the number of detectable civilizations in our galaxy.

After reading All These Worlds Are Yours by Jon Willis, I’ve come to think of the Drake equation as a to-do list for astrobiologists.

N = R* · fp · ne · fl · fi · fc · L
  • Figure out how many stars are born in our galaxy per year (R*).
  • Figure out how many of those stars have planets (fp).
  • Figure out how many of those planets could support life (ne).
  • Figure out how many planets that could support life actually do (fl).
  • Figure out how often life evolves into intelligent life (fi).
  • Figure out how often intelligent life develops radio communications that we could detect (fc).
  • Figure out how long the average intelligent civilization keeps its radio equipment working (L).

Like I said, it’s a to-do list.  It’s presented in the form of an equation because… well, you know… scientists.

At this point, we have a pretty good feel for the first two variables in the Drake equation.  As stated in this article from Astronomy Magazine, 1.5 to 3 new stars are born per year in our galaxy, and each star has at least one planet, on average.  Current and upcoming missions should start to pin down real numbers for the number of planets that could potentially support life.

Beyond that, those questions do get progressively harder, but astrobiologists are steadily working their way down their to-do list—or rather, they’re working their way through the equation, starting from the left and heading to the right.  Answers are coming, slowly but surely.

Next time on Sciency Words A to Z, when astrobiologists talk about Earth-like planets, what exactly does that mean?