Latitude, Longitude and Time — The Grid Explained

Two Sets of Lines

Latitudes run east–west and measure distance north or south of the Equator. They are also called parallels because they never meet.

• ›Equator = 0°, the longest latitude
• ›Poles = 90°N and 90°S, which are points, not lines
• ›Total: 181 latitudes counting the Equator

Longitudes run north–south, pole to pole, and measure distance east or west of the Prime Meridian. They are called meridians.

• ›Prime Meridian = 0°, passing through Greenwich, London
• ›All longitudes are equal in length and all meet at the poles
• ›Total: 360 meridians

The key asymmetry: latitudes differ in length, longitudes do not. That is why one degree of latitude is a fixed distance (~111 km) but one degree of longitude shrinks as you move toward the poles.

1. Indian Standard Time is based on which longitude?

2. One degree of longitude corresponds to how much difference in time?

3. The Tropic of Cancer passes through how many Indian states?

4. If it is 12:00 noon at the Prime Meridian, what is the local time at 45°E?

5. Which is the only latitude that is a great circle?

6. The total number of latitudes, including the Equator, is:

7. Crossing the International Date Line from east to west, a traveller must:

8. The Earth's axial tilt, which causes the seasons, is approximately: