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We will start at the longitude where Sun is on the meridian (the north
south
line), noon local time. The direction overhead is always the same
and
the direction toward Sun is constantly changing. You would see
Sun
appear to move across the sky, until after one quarter of a revolution
it
would set. After half a revolution your meridian, still pointing
the
same direction, would be pointing directly away from Sun, midnight
local
time. At three quarters of a revolution Sun would rise.
Having
completed one revolution, Sun would again be on your meridian,
completing
exactly one solar day in exactly one year. But it is a retrograde
(negative) day with Sun rising in the west and setting in the east.
(number of rotations / number of revolutions) - 1 = - 1 days per year
Diagram 2B Planet with one rotation per revolution
We will
start at the longitude where Sun is on the meridian (the north south
line), noon local time. Since the planet rotates exactly the same
number
of degrees as it has revolved, you would not see any apparent motion of
Sun
across the sky. After a quarter of a revolution and a quarter of
a
rotation, Sun is still on the meridian, noon. After half a
revolution,
Sun is still on the meridian, noon. After three quarters of a
revolution, Sun is still on the meridian, noon. After one full
revolution, Sun is
still on the meridian, noon. There is never a sunset nor a
sunrise. The "time of day" depends only on your longitude, and
never changes. There is no "day and night".
(one rotation / one revolution) - 1 = 0 days per year
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