Name:
Aim 25: How do we measure time on Earth?
Date:
Do Now: Earth's circumference (around the entire Earth) at the equator is 40,075 km. If it spins once each day, what is the
speed of spinning in km/h? Show work below
I.
Time Zones
The Earth spins towards the east and makes one complete turn in 24 hours. This spinning causes the sun to
appear to move across the sky from east to west. Therefore, it takes 24 hours from when the sun is highest in the
sky (noon) until it is highest in the sky again (noon the next day).
a) How many degrees is in a rotation? (a circle): _____________________
b) How many hours are in a day? _____________________
c) How many degrees does the earth rotate per hour_____________________
d) What did this concept lead to the creation of? _____________________
e) How many time zones are there? _____________________
Time Zone
An area _______degrees wide in which the time is the ______________. They follow lines drawn from
the north pole to the south pole to fit around city, state and country borders
International
Date Line
A line through the Pacific Ocean that marks the divide where the date changes by _________________.
You can’t keep dropping an hour back every 15 degrees & it cannot be two different days in the same
location, so a date is added to the time at the International Date Line (IDL)
Prime
Meridian
A line drawn through Greenwich, England that is the _____________________ point of the worldwide
system of measuring time. In some areas this time is modified in the summer so there are more hours of
daylight in the evening – Daylight Savings Time (DST)
How to read
a Time Zone
Map
•
when heading ___________ you _______________ hours.
•
The Earth spins towards the ____________. So when you head east you ____________ hours and
For every time zone (section) you move over, you will add or subtract one ______________
Time Zone Map
1. If it’s 9am Monday in Florida, what date and time is it in:
Hawaii: _________________________________________
Russia: _________________________________________
Argentina: ______________________________________
Greenland: ______________________________________
Australia (Eastern part): __________________________
2. How many hours after the sun rises at point F will the sun rise at the International Date Line? ____________
3. On the United States time zone map provided below, indicate the standard time in each time zone when it is 9 a.m. in
the Central time Zone. The dashed lines represent the standard-time meridians for each time zone. Be sure to indicate
the time for all three zones.