Unnderstanding Longitude & Latitude

This is an example of a typical graph we are all familiar with. The graph is made up of different “points” with lines that connect the points.

Each point has two values: The “X” value that runs along the horizontal “X” axis The “Y” value that runs along the vertical “Y” axis Typical Graph Y axis X axis

X value is always stated first Followed by the Y value The “origin” is the point where the 2 axes intersect with a value of (0,0) Typical Graph Y (3,8) (9,5) X (0,0)

A point can also have negative (-) values Negative X values are to the left of the origin (0,0) Negative Y values are below the origin Typical Graph Y (-X,+Y) (+X,+Y) (0,0) X (-X,-Y) (+X,-Y)

East West, North South on The Earth Let the X axis be the Equator. Let the Y axis be the Prime Meridian that runs through Greenwich outside of London. Lat/Long are the 2 grid points by which you can locate any point on earth. Y X

East West, North South on the Earth Let each of the four quarters then be designated by North or South and East or West. N W E S

East West, North South on the Earth The N tells us we’re north of the Equator. The S tells us we’re south of the Equator. The E tells us that we’re east of the Prime Meridian. The W tells us that we’re west of the Prime Meridian. (N, W) (N, E) (S, W) (S, E)

East West, North South on the Earth That means all points in North America will have a North latitude and a West longitude because it is North of the Equator and West of the Prime Meridian. (N, W) Prime Meridian

East West, North South on the Earth What would be the latitude and longitude directions in Australia? ? Prime Meridian If you said South and East , you’re right!

Lines of longitude only Equator added Other lines of latitude added

Cross-section through line of longitude Cross-sections through lines of latitude

Orange cut through lines of longitude Orange cut through lines of latitude

Prime Meridian The Prime Meridian (0°) and the 180° line split the earth into the Western Hemisphere and Eastern Hemisphere. Prime Meridian Western Hemisphere Eastern Hemisphere Places located east of the Prime Meridian have an east longitude (E) address. Places located west of the Prime Meridian have a west longitude (W) address. TEKS: Social Studies – 6.22 (A), Using social studies terminology correctly 7.22 (A), 8.31 (A) 14

INTERNATIONAL DATE LINE 180° SEPARATES 2 CALENDAR DAYS. America to Asia – gain a day Asia to America – lose a day If you took a cruise on a ship, circumventing, or traveling around the entire planet, you would experience firsthand a phenomena that would help you understand the importance of an international dateline. An explorer by the name of Ferdinand Magellan did just that in the year 1519. Magellan along with 241 men set out to travel around the entire Earth. These men kept very careful records as they traveled. Yet, when they returned, they found that their calendars were off by one day with the calendars of everyone in their home countries. What happened? How did these men loose an entire day? The day was not lost all at once. It was lost little by little, as the traveled around the Earth. If you stay in one place, a day lasts 24 hours. However, if you travel the opposite direction of the rotation of the Earth, your day will be slightly longer than 24 hours, because you are traveling ahead of the setting sun. If you travel with the rotation of the Earth, your day will be slightly shorter than 24 hours, because you are traveling into the sunset. At any one moment there are actually two days on the Earth at the same time. A new day begins at mid-night on the International Dateline. It travels around the Earth, until 48 hours later it ends back at the International dateline. If you were to travel across the International Dateline, the date would change either forward, or backward. This line actually lies in the middle of a time zone. This means that the hour on the clock would not change, as you crossed over, just the date. 15

Latitude is the distance from the equator along the Y axis. All points along the equator have a value of 0 degrees latitude. North pole = 90°N South pole = 90°S Values are expressed in terms of degrees. What is Latitude? 90°N Y X 90°S

This is also true of longitude. What is Latitude? Each degree of latitude is divided into 60 minutes. Each minute is divided into 60 seconds. 90°N Y X 90°S This is also true of longitude.

This is close to the latitude where you live. What is Latitude? For Example: 40°, 06’,59’’N This is close to the latitude where you live. 90°N Y X 90°S

What is Longitude? Longitude is the distance from the prime meridian along the X axis. All points along the prime meridian have a value of 0 degrees longitude. The earth is divided into two parts, or hemispheres, of east and west longitude. Y X 180°W 180°E

The earth is divided into 360 equal slices (meridians) What is Longitude? The earth is divided into 360 equal slices (meridians) 180 west and 180 east of the prime meridian Y X 180°W 180°E

Our latitude and longitude might be: What is Latitude? Our latitude and longitude might be: 40°, 06’,59’’N 88°, 14’, 35’’W 90°N Y X 90°S

(0,0) is off the western coast of Africa in the Atlantic Ocean. The origin point (0,0) is where the equator intersects the prime meridian. (0,0) is off the western coast of Africa in the Atlantic Ocean. So Where is (0,0)?

In Summary!

Positioning on the Earth’s Surface East is the direction of rotation of the Earth Equator Latitude 0o Latitude: (90oN to 90oS) North Pole South Pole Prime Meridian 0o Longitude Longitude: (180oE to 180oW) Longitude 60o West Longitude 30o West Longitude 60o East 90o Longitude 30o East 66½o Latitude 23½o North Tropic of Cancer 23½o 21st June 22nd December 22nd Sept 20th March 90oW 60oW 30oW 90oE 30oE 60oE 23½o 900 Latitude 23½o South Tropic of Capricorn Longitude 90o West Longitude 90oEast Latitude and Longitude together enable the fixing of position on the Earth’s surface.