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- We arrive
at the formula:
Distance of the Sun = 110 x 112 x Diameter of Venus.
How big is Venus?
- We answer
this question by making a rather big assumption: That Venus, being
a planet like the Earth, is approximately the same size as the
Earth. You may question this assumption, and rightfully so. Why
have we made this rather large assumption? Basically to have a
method for measuring the Earth Sun distance that anyone can do.
We make the assumption in the interest of simplicity.
- But Venus
may not be the same size as the Earth, you may protest. Justifiably.
What we will get in that case is only a very rough idea of how
far the Sun is from us. However, the assumption we have made is
luckily pretty good. Venus is as big as the Earth within
a margin of less than 10 percent! Had Jeremiah Horrocks
made this assumption he would have gone down in history as the
first person to measure “How far to the Sun?” (Like Anaxagorus,
Horrocks made the wrong assumption and obtained an answer
which was the correct answer to a different question : How
far is Venus from the Sun? )
- So, if Venus
is as big as the earth, to get the diameter of Venus, we must
only measure the diameter of the earth.
- Because
we have assumed that Venus and the earth are the same size, we
have the following formula : Distance of the sun = 110 x 112
x diameter of the earth
- We now need
to find out how big is the earth
to complete our calculation
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