Ask A Scientist© Astronomy Archive

 >>    name         Marcelo
 >>    status       student
 >>    age          20s

 >>    Question -   1)Is the distance from the earth to the sun measure in
 >> light years or miles?
 >>2)How many miles or light years are there between the earth and the sun?

You can measure it in any unit of length.  You could measure it in
millimeters if you wanted.

The distance between the earth and the sun is not constant.  The earth's
orbit around the sun is nearly circular, but not perfectly so.  The earth
is actually closest to the Sun in the northern hemisphere winter.  I'm not
certain of the time of closest approach, though.

On average, the distance between the earth and the sun is 93 million miles.
This is not anywhere near a light-year.  It is more like 8.3 light-minutes.


                Richard Barrans Jr., Ph.D.
                Chemical Separations Group
                Chemistry Division CHM/200
                Argonne National Laboratory
                9700 South Cass Avenue
                Argonne, IL 60439
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The distance between the earth and the sun is 93,000,000 miles.
The time it takes light to travel this distance is 93,000,000
miles/186,000 miles/sec or 500 seconds. Hence the time is 500sec/60 or
8.333 minutes. What fraction of a year is 8.333 minutes, well that is
8.333/(60x24x365) = or 0.00001585 light years.
You can express the distance either way, but in this case 93 million
miles makes more sense.

H. Myron
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Marcelo,

We measure the distance in miles, 93 million or so to be exact.
A light year is defined as the distance light can travel in one year.
Lights moves at the speed of 186,000 miles per second.  Therefore, light
from the sun does not take a year to reach us, since it is, by comparison
with other starts, relatively close to us .  If you consider light from the
sun must travel 93,000,000 miles and is moving at 186,000 miles per second,
the light takes only about 8.3 minutes to reach us.

Light years as a measurement of distance is most useful when we are
discussing extremely distant galaxies, etc..  Using 186,000 miles per second
as the speed of light, we find it can travel
5865696000000 miles in one (average) year.  The sun, in light years, is only
0.00001585 light years away, so miles is a better unit to use.

Thanks for using NEWTON!
Dr. Rupnik
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93 million miles
8 light minutes (.25 millionths of a light year)

Tim Mooney 
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