Probably thousands of Alien Civilizations

Are there aliens out there in space?

How many alien civilizations are there?

Why haven’t aliens communicate with us?

Astrophysist Frank Drake wanted to encourage astronomers to consider alien civilizations.  SETI, the Search for Extra Terrestrial Intelligence was just beginning and needed funding.

So one day at Greenbank West Virginia, taking a break form observing with the giant radio telescopes there, put pen to paper and created the Drake Equation.  There is a plaque the in that room commemorating that equation. (See the featured image.)

There is an interactive version of the Drake equation at this BBC web site.    At that BBC site, you can change the number of each variables.

I calculate almost two thousand advanced alien civilizations right now in our Milky Way galaxy.

N* is the number of detectable civilizations in the Milky Way.  We will solve for N*.  Here’s the Drake Equation:

N* = R* fp Ne   fl  fi   fc   L  Nr


How many new stars begin fusing hydrogen into helium each year in our galaxy?  Recent observations indicate that 7 new stars appear annually, not ten.  The January 5 issue of Nature magazine describes the research,

Our star, the Sun


What percentage of stars have planets?  Scientists use to estimate this at about 50%  The Kepler space telescope has shown us that just about every star observed has at least one plant.


How many of those planets would be like the Earth?  For our solar system, I count one

Screen shot 2015-01-10 at 1.07.26 AM
Our largest planet, Jupiter

Earth-like planet for 8.


How many Earth-like planets will have life?  Right now our one example shows us 100%  I’m going to be a little conservative here and say 50%


What’s the chance that that life will become intelligent?  Again, our one example is 100% and again I choose to be conservative at 50%


What’s the chance that intelligent life will develop communication like radio?  Again I go 50%

iPhoto Library 218
Radio Telescope, South Africa, 2004


How long will such a civilization last on average?  I’m going very conservative here.  Let’s hope we last a million years.


How many times can our civilization bounce back from a catastrophe.  Nuclear War, Climate change, Killer Asteroid?  I guess once.

Do I believe in aliens?

No, I don’t, and…

Dennis and Marvin
Me with Marvin the Martian at Mars Analog Research Station in Utah

For my best guess at the variables, I calculate a mere 1,929 intelligent, communicating civilizations in our galaxy right now.

That’s about 300 trillion in the whole known universe.  I think alien civilizations are probably out there.




3 thoughts on “Probably thousands of Alien Civilizations

  1. That plaque it’s fabulous!! I’m actually thinking of getting the equation tattooed on my left forearm (I have no other tattoos)!


  2. It worries me that there aren’t more signs of intelligent life out there . Considering how long it took intelligent life to develop on our planet it seems that even though a planet may be capable of intelligent life that the window of time that intelligent life is there could be extremely small. Also given how quickly we have advanced technologically in the last few centuries especially the last 50 years compared to how long earth has been habitable ,shouldn’t it be likely that at least one other intelligent civilisation has progressed far enough technologically elsewhere that we would have detected their presence in some way with our current technology e.g. long range communications and travel methods?


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