How is this view of Earth's daily cycle similar to a clock?
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|Did you notice?
line between darkness and daylight seems to move clockwise, like the hands on a
Why Behind What You See
The Earth rotates on its axis. It makes one full turn every 24 hours.
clocks show these 24 hours, too. Most are divided into 12 a.m. and 12
p.m. hours. When we want to use a standard time that's
the same everywhere on Earth, we use Greenwich
Mean Time (GMT), also called Universal Time (UT). This is based on
a 24-hour clock.
The Earth is divided into 24 time zones. All clocks in the same time
zone show the same time. Each time zone is an hour earlier than next zone
east and an hour later than next zone west. On the equinox, as shown in
the animation above, each hourly movement of the sun roughly shows the
movement from one time zone to the next.
day, the earth rotates once on its axis, which equals 360 degrees.
are 24 hours in a day. How many degrees longitude does the earth turn
- The earth is divided into 24 global time zones. How many
degrees of longitude does each one cover? (See answer, below.)
- 360 degrees ÷ 24
hours = 15 degrees per hour.
- Each time zone covers 15 degrees of longitude.