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Re: Astronomical Unit (AU)



Doesn't this all depend upon the precision required?
I think 8 minutes is good enough for younger children.
As they get older then we can get more precise.

What crossover age would you suggest? The number is not
important until such time as it is needed for calculation.
At that time eight minutes certainly won't do, and there
is no need to be imprecise since the accurate value is
well known.

Why not say to younger children "Light from the Sun takes
more than eight minutes to reach us"? That would be a
better way to put it, in my view. The information should
also be accompanied by some indication of how fast light
travels. Saying that a trip of that distance made in the
family car at sixty miles per hour would take more than
175 years should put a good referent to it. It is
difficult to get any real physical sense and feeling for
numbers like the astronomical unit or the speed of light
without actually doing some calculations, but children
are capable of getting some impression of the immensity
of the solar system and the incredible celerity of light.

(The common scientific literacy test answer would be
eight minutes for adults, and some of those would think
it means *exactly* eight minutes. The number is "out
there". Many also know that the AU is 93 million miles.
That number is good to better than 0.05%, more accurate
than the number Canadian school children learn: 150
million kilometers.)

Leigh