Earth Science
Using a Globe Lab
Name: __________________________
Period: ______________
A. Latitude and Longitude
Latitude is distance (in degrees) north or south of the Equator; it is
measured by parallels. The latitude of the Equator is 0. The latitudes of the
north and south poles are 90N and 90S respectively. The latitude of Phoenix
is 33N; it is 33 north of the Equator.
Longitude is distance (in degrees) east or west of the Prime Meridian. It is
measured by meridians. The Prime Meridian passes through Greenwich, England
and its longitude is 0. Exactly halfway around the Earth from the Prime
Meridian is the International Date Line; its longitude is 180 (E or W). The
longitude of Phoenix is 112W; it is 112 west of the Prime Meridian.
Any place on Earth can be located by reading off its latitude and longitude
coordinates (in degrees). For more precise locations, each degree of longitude
and latitude are divided into 60 equal parts called minutes (symbolized as ‘).
Likewise, each minute is divided into 60 equal parts called seconds (symbolized
as “).
1. Use a globe to find the name of the place located at each of the following
pairs of coordinates:
a. 15N, 90W
c. 81S, 180
b. 50S, 60W
d. 45N, 60E
2. Give the coordinates for each of the following places:
a. Honolulu, Hawaii
c. Tokyo, Japan
b. London, England
d. Sydney, Australia
B. Magnetic Declination
The two natural points for describing location on Earth are the axis of
rotation. These points are called the true North and South Poles. They are the
points around which the rest of the world rotates. All longitude lines come
together at the poles. The North Star (called Polaris) is located directly above the
true North Pole. The poles define true directions on Earth.
Another point, useful for determining directions on Earth is the Magnetic
North Pole. The Magnetic North Pole is the place towards which all compasses
point. It is located in the Northwest Territories of Canada near Prince Wales
Island. (Find it on your globe).
On most maps, a line drawn straight from the bottom to the top would point
to true north. This is usually shown by an arrow-pointing north. The map may also
show an arrow pointing to magnetic north. The angle between these two directions
is called magnetic declination. If you are using a map and a compass, it is important
to realize that the compass does not usually point exactly toward true north. Your
compass must be set at the appropriate magnetic declination for your location.
3. After reading the above information, write your own definition for:
a. True North Pole
b. Magnetic North Pole
c. Magnetic declination
4. Give the latitude and longitude coordinates of:
a. True North Pole
b. Magnetic North Pole
5. Locate the following places on the globe. If you were standing in the place,
what true direction would a compass be pointing?
a. Godhaven, Greenland
c. Dallas, Texas
b. Point Barrow, Alaska
d. The True North Pole
C. Great Circles
Any circle that cuts the Earth into two equal halves is a great circle. The
Equator is a great circle but other parallels are not. The Prime Meridian and the
International Date Line together trace out a great circle. So do all other
corresponding pairs of meridians. Any line drawn around the largest part of the
Earth (no matter what its orientation) is a great circle.
Great circles are important for global navigation. The shortest distance
between any two places on Earth is traced out by the great circle that would
cut the Earth in half along that path.
The shortest distance between two points on a flat (distorted) world map is
not a straight line. For example, in traveling from Phoenix, Arizona to Cairo,
Egypt, it is shorter to go north from Arizona rather than directly east. Find
both cities on a flat map and on the globe and compare the distance of the two
directions.
To find a great circle route between any two places on a globe, simply
stretch a string between the two points until it takes the shortest distance.
6. Write your own definition for a great circle.
7. Explain why global navigators want to follow great circle routes.
8. In what direction would you travel to take the following trips by the
shortest route?
From:
a. Arizona
b. Brisbane, Australia
c. Cairo, Egypt
d. Casablanca, Morocco
e. Ecuador, South America
To:
India
Paris, France
Uruguay, South America
Tokyo, Japan
Kenya, Africa
9. When should you travel directly east or west to take the shortest route?