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.

EquatorA 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