Chapter 1: Locating Places on the Earth
Chapter outline
1. Introduction2. Map and it's components
2.1 Types of Map
2.2 Components of map
3. Mapping the Earth
Introduction
A map is a visual representation of an area, showing the locations of different features such as mountains, rivers, cities, and roads.
A map is a hidden treasure. It guides you to places you’ve never been. Maps aren’t just for treasure hunts; they help us understand our world, navigate cities, and explore new lands.
A Map and Its Components
Maps can be simple or complex, depending on the amount of detail they include.
There are different types of maps, each serving a specific purpose:
- Physical Maps: Show natural features like mountains, rivers, and lakes.
- Political Maps: Show boundaries of countries, states, and cities.
- Thematic Maps: Focus on specific types of information, such as population density or climate zones.
Components of a Map
Maps have several important components that help us understand the information they provide:
- Distance: Maps use a scale to represent distances. The scale shows the relationship between the distances on the map and the actual distances on the ground.
- For example, a scale might show that 1 cm on the map equals 500 meters in reality.
- Direction: Maps use main directions (North, South, East, and West) and in-between directions (Northeast, Southeast, Southwest, and Northwest) to help us find places.
- Most maps have an arrow pointing to the north to show which way is north. The four big arrows in the following picture show the four main directions: North, South, East, and West.
- Symbols: Maps use symbols to represent different features.
- For example, a small drawing of a tree might represent a forest, or a dotted line might represent a road. These symbols are explained in the map's legend or key.
Mapping the Earth
The Earth is a sphere, so representing it on a flat map can be challenging. A globe is a more accurate way to represent the Earth because it maintains the correct proportions and distances.
However, maps are more convenient for many purposes.
To accurately locate places on the Earth, we use a coordinate system based on latitudes and longitudes.
(a) Understanding Coordinates
A coordinate system uses one or more numbers to uniquely determine or identify the position of a particular point.
In the case of earth, latitudes and longitudes are used to determine or pinpoint the position of a particular place.
These are imaginary lines drawn on the earth that assist in location and navigation across the planet.
The position of a point on earth written in terms of its latitude and longitude is called its coordinates.
(b) Latitudes
Equator: The Equator is an imaginary line that circles the Earth halfway between the North and South Poles. It is at 0° latitude. The equator divides the earth into southern and northern hemispheres.
Parallels of Latitude: These are imaginary lines that run parallel to the Equator. They measure the distance north or south from the Equator. For example, the Tropic of Cancer is at approximately 23.5°N latitude, and the Tropic of Capricorn is at approximately 23.5°S latitude.
Climate Zones: The Earth is divided into different climate zones based on latitude.
The area near the Equator is generally hot and is called the torrid zone.
The areas between the tropics and polar circles are called temperate zones and have moderate climates.
The areas near the poles are called frigid zones and are very cold.
(c) Longitudes
Prime Meridian: The Prime Meridian is an imaginary line that runs from the North Pole to the South Pole through Greenwich, England. It is at 0° longitude. The prime meridian divides the earth into the eastern and western hemispheres.
Meridians of Longitude: These are imaginary lines that run from the North Pole to the South Pole. They measure the distance east or west from the Prime Meridian. For example, New York is at approximately 74°W longitude, and Tokyo is at approximately 140°E longitude.
Local Time: The Earth's rotation causes different places to experience day and night at different times. Local time is determined by a place's longitude. Places with the same longitude have the same local time.
Understanding Time Zones
The Earth completes a rotation about its own axis every 24 hours. A full 360° rotation represents 24 hours, so 1 hour can be represented by 15° of rotation of the Earth.
So, the Earth is divided into 24 time zones, each 15° of longitude wide. Each time zone represents one hour of time. For example, if it is 12 pm (noon) at Greenwich (0° longitude), it is 1 pm at 15°E longitude and 11 am at 15°W longitude.
Countries often adopt a standard time for the entire country, based on the time at a specific meridian. For example, Indian Standard Time (IST) is 5.5 hours ahead of Greenwich Mean Time (GMT).
The International Date Line is an imaginary line located around 180° longitude. When you cross this line, the date changes by one day. If you cross it moving eastward, you subtract a day. If you cross it moving westward, you add a day.
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Exercise Questions and Answers
Q1. Returning to page 10 and to Fig. 5.2 in Chapter 5 of this textbook, taking the scale to be 2.5 cm = 500 km, calculate the real distance from the estuary of the Narmada River to the estuary of the Ganga River.
Answer: If the distance measured on the map is about 4 cm, then:
4 cm × 200 km per cm = 800 km (approx.).
(Exact distance depends on your measurement, but it is around 800–900 km).
Q2. Why is it 5:30 pm in India when it is 12 pm or noon in London?
Answer: India’s Standard Time is 5 hours 30 minutes ahead of Greenwich Mean Time (GMT). So, when it is 12 pm in London (GMT), it is 5:30 pm in India.
Q3. Why do we need symbols and colours in the map?
Answer: Symbols and colours are used to represent features (like rivers, roads, boundaries, etc.) in limited space. They make the map simple, clear, and easy to understand.
Q4. Find out what you have in the eight directions from your home or school.
Answer: (This is an activity-based question; students should draw or note landmarks. Example:)
North – Market
South – Park
East – School
West – Railway Station
NE – Temple
SE – Bus Stand
SW – Hospital
NW – Library
Q5. What is the difference between local time and standard time?
Answer:
Local Time: Time calculated for a specific place based on its longitude (when the Sun is overhead at that place, it is 12 noon local time).
Standard Time: A uniform time adopted by a country or region for convenience, usually based on one central meridian.
👉 In India, IST (82.5°E longitude) is the standard time, though local times differ across the country.
Q6. Delhi’s and Bengaluru’s latitudes are 29°N and 13°N; their longitudes are almost the same, 77°E. How much will be the difference in local time between the two cities?
Answer: Since their longitudes are the same, there is no difference in local time. The difference in latitude does not affect local time.
Q7. Mark the following statements as true or false; explain your answers with a sentence or two.
1. All parallels of latitude have the same length.
❌ False – They get smaller as we move towards the poles.
2. The length of a meridian of longitude is half of that of the Equator.
✅ True – A meridian is a semicircle from pole to pole, while the Equator is a full circle.
3. The South Pole has a latitude of 90°S.
✅ True.
4. In Assam, the local time and the IST are identical.
❌ False – Assam is ahead of IST by about 1 hour, but we follow IST as standard time.
5. Lines separating the time zones are identical with meridians of longitude.
❌ False – They are adjusted to follow political boundaries.
6. The Equator is also a parallel of latitude.
✅ True – It is the longest parallel of latitude (0°).
Q8. Solve the crossword.
Across
1. Scale – Lets you squeeze a huge area into your map
2. Globe – A convenient sphere
3. Equator – The longest parallel of latitude
4. Greenwich – The place the Prime Meridian is attached to
5. Compass – So convenient to find your way
6. Latitude – A measure of the distance from the Equator
Down
2. Longitude – A measure of the distance from the Prime Meridian
3. Coordinates – These two together allow us to locate a place
6. Grid – What latitudes and longitudes together create
7. IST – The time we all follow in India
9. North Pole – On top of the world
11. IDL – An abbreviation for a line across which the day and date change
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