1. Lines of Longitude
* Definition: Lines of longitude are imaginary circles that run from the North Pole to the South Pole, dividing the Earth into sections like slices of an orange.
* Measurement: Each line of longitude is measured in degrees, starting at the Prime Meridian (0° longitude) which passes through Greenwich, England.
* East vs. West: Locations east of the Prime Meridian are assigned positive longitude values (1° E, 2° E, etc.), while locations west of the Prime Meridian have negative longitude values (1° W, 2° W, etc.).
2. Using Longitude to Determine East and West
* Comparing Longitudes: To determine if one location is east or west of another, compare their longitude values:
* If location A has a higher longitude value (e.g., 10° E) than location B (e.g., 5° E), then location A is east of location B.
* If location A has a lower longitude value (e.g., -10° W) than location B (e.g., -5° W), then location A is west of location B.
3. Other Considerations
* International Date Line: At 180° longitude, the International Date Line separates calendar days. If you cross the line traveling west, the date advances by one day. If you cross traveling east, the date moves backward.
* Time Zones: Longitude is closely linked to time zones. The Earth is divided into 24 time zones, each roughly 15° of longitude wide.
Example
* New York City is located at approximately -74° W longitude.
* London is located at 0° longitude (the Prime Meridian).
* Therefore, New York City is west of London.
Visualizing Longitude
Imagine a globe of the Earth. Lines of longitude are like the seams of an orange, running from top to bottom. The Prime Meridian is the seam that goes through Greenwich. To find the east-west position of any point on Earth, you can trace a line along the seam of longitude until you reach the Prime Meridian.
