interesting question


A guy on the radio just said that he knows a lobbyist. He got
her tipsy one time and asked her if she thought that the American
electorate was stupid. She didn't hesitate but just said "Yes",
then added that most of the electorate don't know how many
days it takes for the earth to go around the sun.

That's not such a simple question. It takes about 365.24 days,
but only if you define a day as (366.24/365.24) rotations of the
earth around its own axis. That time is what most people mean
by a day, but they're probably not aware that a day is not
exactly equal to one rotation of the earth around its axis.

I had to think about that, and I think that answer is correct.
I thought it might be (364.24/365.24) instead of (366.24/365.24)
until I physically faced my head south and imagined that the
earth must be rotating west to east to make the sun appear
to rise in the east and set in the west. Since most rotational
motions in the solar system are in the same direction (excluding
a few moons and comets), that means that by the time the
earth has completed one rotation on its axis, it has moved a
little further west in its orbit with respect to the sun, so the
sun appears to be a little bit east of where it was with respect
to earth than it was when the rotation started. That means
the earth must rotate slightly more than once on its own axis
to make the sun appear to be in the same place in the sky
the next day (on average over a year: see "analemma" in
wikipedia).

Actually 325.2425 is more accurate for the length of the
year, since we have leap years every four years, excluding
years that are divisibly by 100 but not also divisible by 400.
(That's why 2000 was a leap year though 1700, 1800, and
1900 were not.) Even that's not perfect of course.
According to Wikipedia, a more accurate figure is
365.242374 years, but even that doesn't account for
unpredictable variations in the earth's rotation, due to
shifting of weight due to earthquakes and sub-surface
movements and whatnot. Enter "Leap Year" in
wikipedia to see the figure and a chart.

.

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