4.2
Earth’s Rotation
• Rotation
• Earth spinning on its
axis
• Earth takes 24 hours
or 1 day to make one
complete rotation
• Rotation causes day
and night
• Evidence of Earth’s
rotation
• Foucault’s Pendulum
– Pendulum swing
changed every hour,
evidence that earth was
turning under it
• Coriolis Effect
– Winds are deflected
(turned) toward the
west….due to Earth
spinning or rotating
toward the east
• Axis
• Earth is tilted on its
axis 23.5o
• Time
• 24 hours in one day
• 24 standard time zones
on Earth (15o of
longitude each)
• Prime Meridian
• Move westward –
move clocks back to
an earlier time
• Move eastward –
change clocks to a
later time
• International Date
Line
• When travelers cross
the International Date
Line, they change their
calendar by one day
• Move westward, go
ahead a day