### Philip Plait

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#BAFact: To scale, if the Earth/Sun distance were one inch, a light year would be exactly one mile.

A little bit of fun math for you: if you made a scale model of the solar system where the distance from the Sun to the Earth were one inch, then a light year in the model would be almost precisely a mile in the real world. How cool is that?

I do the math here: http://blogs.discovermagazine.com/badastronomy/2012/06/18/bafact-math-give-him-an-inch-and-hell-take-a-light-year/﻿
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Almost precisely is almost always cool!﻿

Nice, but the metric system still is more practical...﻿

3 significant digits - that's exact to an astronomer. :)﻿

When distances between objects are measured, are they generally measured edge-to-edge or center-to-center? I could see edge-to-edge being problematic for objects that are fluid.﻿

And this is why trying to design space games for tabletop is such a pain in the rear.﻿

Well, duh... I phrased my question poorly: what units?﻿

center-of-gravity to center-of-gravity﻿

Sometimes even an order of magnitude is good enough (1 sf)﻿

It still seems like a light year would be longer.﻿

Those of us in the US don't have to translate street signs if we just use one arbitrary distance measure over another.﻿

Except of course when sending probes to Mars. Ooops ;-)﻿

In astronomy, the distances between objects is generally so large, and our measurements are generally so poor, that the distinction between edge-to-edge or centre-to-centre measurements is meaningless.

For instance, the difference between measuring from the surface of the Earth to the "surface" of the Sun, and measuring from the centre of each is less than one-half of one percent.﻿

Neat, also shows the giant scale of a light year.﻿

Hey, as long as we're on G+, why not use Google's calculator to give you the answer?  Go to google.com and type:

(5280 * 12) / ( 1 light year / 1 au )

You will get the answer "1.00190273", meaning that you're less than 0.02 percent off.﻿

I'm with  .  I mean, 5280 x 12 inches to a mile?  ﻿

Miles and inches. Sigh.﻿

Didn't  post a question to this effect on Google Plus a month or two back?﻿

, it makes as much sense as 20*12 pennies to a pound.﻿
Josh W

Philip has successfully blown my mind once again. Thank you sir!﻿

Dear Phil, what is an inch?  Is that one of those ancient measurements like a cubit or a furlong?﻿

An inch is what a centimeter measures if it eats too much fast food.﻿

I just googled "AU mile in light year inches" and it replied "1 Astronomical Unit mile = 1.00190273 light year inches". So, correct you are. :-)﻿

Hey, , maybe that relationship could be used as the starting point for some sort of Golden Rule for determining inhabitable planets...﻿