Maps as models of the Earth

You are here

Map - is a representation of the features of a physical body such as Earth.

Ptolemy Map

European Maps

Europeans’ placed East at the top to emphasize the importance of Jerusalem to the Europeans’ faith.

Chinese Maps

The Chinese put south at the top of their maps because nothing to the north held any interest to them.

The Greeks

Accepted the Earth as being a sphere almost 2,000 years before Christopher Columbus made his voyage in 1492.

Eratosthenes – A Greek mathematician, wanted to know the size of Earth.› Calculated the circumference using math and

observation of the sun.› No Satellites or computers were used just pen

and paper.› His calculations were off by 6,250km. Roughly

4,000miles.

Eratosthenes

Finding Direction on Earth

Reference Point – a fixed place on the Earth’s surface from which direction and location can be described.› Because Earth is spherical it doesn’t really

have any reference points or does it?

Reference Points on Earth

Axis – the imaginary line that runs through the Earth.› At each end of the axis is the geographic

poles: North Pole South Pole

Cardinal Directions

Cardinal Directions – The popular directions of North, South, East, and West.

What are the advantages of Cardinal Directions?

Using a Compass

Compass – a tool that uses the natural magnetism of the Earth to show direction.› The Earth has two different sets of poles

Geographic Poles – The location in which the Earth spins on its Axis.

Magnetic Poles – The poles that the compass will point to.

True North and Magnetic Declination

True North – the direction to the geographic North Pole› You must make a correction for the difference

between the geographic North Pole and the magnetic north pole, in order to use a compass.

Magnetic Declination – the difference between the magnetic north and the true north.› Must be calculated in order to use a compass.

Using Magnetic Declination

Magnetic declination is measure in degrees east or west of true north. (pg 39 fig 5)› Figure out roughly what the magnetic

declination is for New Bern, NC.› Remember CEEC ( Correct Easterly Errors

Clockwise)

Magnetic Declination

Finding Locations on the Earth

Just like you have an address at your house city’s, states, and islands have an address too.› The address includes two very important

geographical terms. Longitude Latitude.

Latitude

Latitude – Imaginary lines drawn around the Earth parallel to the equator. › Tells distances North or South of the

equator.› Expressed in degrees.

Equator

A circle located halfway between the North and South Poles that divides the Earth into the Northern and Southern Hemispheres.› Represents 0° latitude› Divides the Earth into Northern

Hemisphere and Southern Hemisphere.

Latitude

Latitude

North Pole and South Pole› Located at 90°› Pg 43 fig 3-1

Longitude

Longitude – lines of longitude, or meridians, are imaginary lines that pass through both poles.› Distance East and West of the prime

meridian.› Expressed in degrees.› Lines run North and South of Equator and

are farther apart at the equator.

Longitude

http://earthguide.ucsd.edu/earthguide/diagrams/globe/globe.swf

Prime Meridian

Prime Meridian – the line that runs from North Pole through Greenwich, England to the South Pole.› Does not run on both sides of the Earth like

the Equator.› Is located at 0°› With the 180 °Meridian line cut the Earth

into two halves West and East. 180 °Meridian line runs on the opposite

side of the Prime Meridian.

Prime Meridian

Prime Meridian/ Meridian

Together the prime meridian and meridian lines divide the Earth into an Eastern and Western hemisphere.

Question

Why is the prime meridian 0 longitude and the meridian 180 longitude when they are the same line dividing the Earth into an east and a west?

Using Latitude and Longitude

There are two ways in which you can use Latitude and Longitude.› To find an object on a map.› To figure out the address of the object.

To find an object on a map.

In order to find and object on a map you must first find the latitude and the longitude of the object.

Second you trace your fingers together and you should be on top of the object or very close to it.

To find the address of an object.

Find the object on the map. Trace your finger out to the longitude

and latitude readings.

Great Circles

Shortest route between two points on a sphere. › Is the same as the shortest point between

two points is a straight line. Used in navigation, especially in long-

distance travel by boat or aircraft.

Longitude Practice

Latitude and Longitude

Crack The Code

End of Section 2.1