# Locating Places on the Earth

## Overview

This chapter introduces the basics of maps and globes, and how to locate places on Earth using coordinates — latitude and longitude. It also explains how time is related to longitudes and introduces key concepts like standard time and the International Date Line. Through visuals, activities, and examples, students develop a foundational understanding of geographic positioning and time zones.

## Key Topics Covered

### 1. What Is a Map?

* A **map** is a visual representation of an area as seen from above.
* Types of maps:

* **Physical maps**: Show natural features (mountains, rivers).
* **Political maps**: Show boundaries, countries, capitals.
* **Thematic maps**: Focus on specific data (climate, population).
* **Components of a map**:

* **Distance**: Represented using a scale (e.g., 1 cm = 500 m).
* **Direction**: Cardinal (N, S, E, W) and intermediate (NE, NW, etc.).
* **Symbols**: Used to depict landmarks and features (post office, road, forest, etc.).

### 2. Coordinates and the Globe

* A **globe** is a spherical model of the Earth, better for representing actual geography than flat maps.
* **Coordinates** help locate any point:

* **Latitude**: Measures distance north or south of the Equator (0°).

* The Equator, Tropic of Cancer (23.5°N), and Tropic of Capricorn (23.5°S) are major lines.
* Climate zones: Torrid (hot), Temperate (moderate), Frigid (cold).
* **Longitude**: Measures distance east or west of the Prime Meridian (0°).

* The Prime Meridian passes through Greenwich, England.
* Longitudes run from 0° to 180°E and 180°W.

### 3. Grid System and Location

* Latitude and longitude together form a **grid** on the globe.
* This allows for precise identification of any place, e.g., Delhi is at 29°N, 77°E.

### 4. Time and Longitude

* The Earth rotates 360° in 24 hours → 15° per hour.
* Each **15° of longitude** corresponds to one hour difference in **local time**.
* Example: If it’s 12 pm at Greenwich (0°), it’s 1 pm at 15°E, and 11 am at 15°W.

### 5. Standard Time and Time Zones

* Using multiple local times in a country would be chaotic, so we use **standard time**.
* **Indian Standard Time (IST)** = GMT + 5 hours 30 minutes.
* Time zones are based roughly on 15° longitude bands but adjust for national borders.
* **International Date Line (IDL)** lies near 180° longitude:

* Crossing IDL **eastward** subtracts a day; crossing **westward** adds a day.

### 6. Ancient Indian Contributions

* Ancient Indian astronomers like **Varāhamihira** used their own Prime Meridian through **Ujjain** (Madhya Rekhā).
* Demonstrates early knowledge of geography and astronomy in India.

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## New Terms and Simple Definitions

| Term | Definition |
| ----------------------- | ------------------------------------------------- |
| Map | A drawing showing areas on Earth |
| Scale | Ratio between distance on map and actual distance |
| Latitude | Distance north or south of the Equator |
| Longitude | Distance east or west of the Prime Meridian |
| Globe | A spherical model of the Earth |
| Coordinates | Set of latitude and longitude to locate a place |
| Prime Meridian | The 0° longitude line |
| International Date Line | The 180° line where date changes by a day |
| IST | Indian Standard Time, 5.5 hours ahead of GMT |
| Time Zone | Region with a uniform standard time |

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## Practice Questions

### Easy

1. **What is a map used for?**
*To represent places on Earth and help locate features.*

2. **What direction is opposite to North?**
*South.*

3. **What is the shape of the Earth?**
*Spherical (nearly round).*

### Medium

4. **What are the main components of a map?**
*Distance (scale), direction (N, S, E, W), and symbols.*

5. **Name one difference between a map and a globe.**
*A globe is spherical and realistic, while a map is flat and easier to carry.*

### Difficult

6. **Why does India have a standard time of GMT +5:30?**
*Because IST is based on a longitude that passes through central India (82.5°E).*

7. **What are the coordinates of Delhi?**
*Approximately 29°N latitude and 77°E longitude.*

8. **Why can’t the Earth be shown accurately on a flat map?**
*Because Earth is spherical and flattening it distorts distances and shapes.*

### Very Difficult

9. **If the difference between Porbandar and Tinsukia is 30° longitude, what is the difference in local time?**
*Each 15° = 1 hour → 30° = 2 hours difference.*

10. **Explain how crossing the International Date Line affects the date.**
*Crossing eastwards subtracts one day, while crossing westwards adds one day.*

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