Dave's Energy

Wednesday, October 17, 2012

Stacking Oil Barrels to the Moon

As a follow-up to my prior post helping to visualize the scale of the world's daily crude oil production, I wanted to provide another "scale" eye opener I often use around the office:

So you have realized now (by reading this post on daily oil production) that we produce enough oil each day such that stacking that production in barrels would reach the moon every 5 days.  But do you really appreciate just how far away the moon is?  Let' use an example to illustrate... and here is where I usually ask someone to draw me a circle representing the Earth, then I ask for another circle representing how big the Moon is in comparison (this usually provides some good fun discussion). The typical answer I get is fairly close, something that looks like this:

In reality, the moon's diameter is about 2160 miles and Earth is about 7926 miles, so the Moon is a bit more than 1/4 the diameter of the Earth, (but it's volume is about 1/50th the Earth).  So the 2-dimensional view to the left is fairly close to correct, at least as far as relative size goes.


But then I ask this: "Can you draw me something more to scale now, showing how far the moon is away from the Earth?"  

I get all kinds of answers, many which look much like the drawing above - they don't change the distance between their drawings and might say, "probably about like that":

So I ask: "You are telling me that if I were to "flip" your flat moon over once, it is close enough that it would touch the Earth after just one flip? You are saying that the Moon is just "one moon-width" away? That usually causes them to re-draw it, maybe moving the Moon over about the distance of one or two Earth diameters.

And while that may seem a good distance, the reality is that the moon is much farther away.  At an average distance of about 238,900 miles from Earth, and with the Earth's diameter being 7,926 miles, that means the Moon is about THIRTY (30) Earth diameters away, or about ONE HUNDRED TEN (110) "Moon-diameters" away.  I then like to draw something on my white-board that looks more like this:



Sometimes my full-wall white board isn't big enough, unless I make sure I draw the initial Earth circle small enough.  Either way, I have to move across the room to finish the drawing. And then I stand back dramatically and let them absorb that and say: "That is how far away the Moon is,   and every five days we stack that much oil up. NOW do you understand just how much we produce every day in this world?.... Crazy, huh?"

Then I challenge them to find me another industry that comes even close to that..."Anyone?.... Anyone....?"

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