"Buchan Meteo" wrote in message
...
Gavino scrive:
"Buchan Meteo" wrote in message
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The earth rotates once each day, 365 times in 365 days, and 366 times
in 366 days when we add a leap day to the calendar year (not to be
confused with a real year).

No, this is what oriel36 asserts himself and is incorrect.

OED
day n. ...corresponding to a rotation of the earth on its axis.

The earth rotates once each day *relative to the sun*

The earth rotates once each day on its axis. That is the definition of a
day. Thus it rotates once per day, or a million times in a million days
because one rotation *is* one day.

Gianna, maybe you're being deliberately obtuse for a laugh (or just to be
awkward!), but please don't fall into oriel36's confusion.

Rotation can only be defined relative so some reference direction, so the
phrase "rotation of the earth on its axis" is imprecise.
The day of 24 hours that we are all familiar with is, as I said, the period
of rotation relative to the sun (actually the mean period, as it varies
throughout the year).

However, since the earth is also moving in orbit around the sun, it is more
logical (on physics grounds) to take the 'true' period of rotation to be
relative to the 'fixed stars'. This is about four minutes short of 24 hours,
as Ian Bingham explained - read his post again if this is not clear.
So in the course of its orbit around the sun in 365.25 days, the earth
actually rotates 366.25 times.

The Foucault pendulum is a good demonstration of this, but simple
observation of the stars (a given star or constellation rises 4 minutes
earlier each day) bears it out.