Aim: How do we find
longitude?
Topic: Unit 1
Main Idea: Time zones
1) How fast does the earth spin?

The earth does one
360 degree spin
every 24 hours so:
360 degrees/ 24
hours=
15 degrees/hour
2) What are time zones?

They are sections of the world 15 degrees
of longitude apart with one hour
difference.
3) What is Greenwich Mean Time?

This is the time on
the prime meridian
where all of the
world sets its time
4) If you are west of the Prime
Meridian your time is ____________,
but if you are east then your time is
______________ because________
_______________________________
___________________________.
5) How do we find longitude using
difference in time?
Step 1: Find the
difference in time in
hours
 Step 2: Multiply by 15
 Step 3: Local time is
earlier=West
Local time is later=East

Summary