Locating Places on the Earth-Notes Social Science Class 6 In English-CBSE Notes

Locating Places on the Earth

Maps

A map is a representation or drawing of an area of the Earth's surface as seen from above. Maps help us locate places and understand different features of the Earth.

• Maps can represent a small area such as a village or a large area such as a country or the whole world.
• Maps are useful for finding locations, directions, distances and geographical features.
• An atlas is a collection of maps in the form of a book.
• Maps may show natural features, political boundaries or information related to a particular theme.

Types of Maps

• Physical Maps: Show natural features such as mountains, rivers, oceans and plains.
• Political Maps: Show countries, states, boundaries, cities and other political features.
• Thematic Maps: Show information related to a particular theme or topic.

Components of a Map

The three main components of a map are distance, direction and symbols.

• Distance: Tells us how far one place is from another.
• Direction: Helps us identify the position of one place in relation to another.
• Symbols: Represent different geographical and human-made features on a map.

Scale

Scale shows the relationship between a distance shown on a map and the actual distance on the ground.

• Scale allows a very large area to be represented on a small map.
• For example, if 1 cm on a map represents 500 m on the ground, the scale is 1 cm = 500 m.
• Scale is important for calculating actual distances from a map.

Directions

• The four main or cardinal directions are North, East, South and West.
• The intermediate directions are Northeast, Southeast, Southwest and Northwest.
• Directions help us describe the position of one place in relation to another.

Map Symbols

Symbols are conventional signs used on maps to represent different features.

• Symbols make maps simple and easy to understand.
• They can represent roads, railway lines, rivers, buildings, boundaries and other features.
• The Survey of India has fixed a set of symbols for maps of India and parts of India.

Globe

A globe is a spherical model of the Earth. It represents the Earth's shape more naturally than a flat map.

• A globe shows the continents, oceans and other major features of the Earth.
• It also helps us understand the position of the Equator, latitudes and longitudes.
• A globe is useful for understanding the Earth as a whole.

Coordinates

Coordinates are used to identify the precise location of a place on the Earth.

• The two coordinates are latitude and longitude.
• Latitude tells us how far north or south a place is from the Equator.
• Longitude tells us how far east or west a place is from the Prime Meridian.
• The intersection of a particular latitude and longitude helps identify a specific location.

Latitudes

Latitude is the measure of the distance of a place north or south of the Equator.

• Latitudes are imaginary lines drawn around the Earth from east to west.
• They are also called parallels of latitude because they are parallel to one another.
• The Equator is the longest parallel of latitude.
• The Equator represents 0° latitude.
• Latitudes are measured from 0° to 90° towards the north or south.
• The North Pole is at 90°N.
• The South Pole is at 90°S.
• The length of the parallels decreases as they approach the poles.

Latitudes and Climate

Latitude has an important relationship with the climate of a place.

• Places near the Equator generally receive more direct sunlight and are warmer.
• Places towards the North and South Poles are generally colder.
• Thus, latitude is an important factor in understanding differences in climate.

Longitudes

Longitude is the measure of the distance of a place east or west of the Prime Meridian.

• Lines of longitude are imaginary half-circles running from the North Pole to the South Pole.
• They are also called meridians of longitude.
• All meridians meet at the North Pole and South Pole.
• The Prime Meridian represents 0° longitude.
• Longitudes are measured from 0° to 180° towards the east and west.
• 180°E and 180°W represent the same longitude.

Prime Meridian

The Prime Meridian is the reference meridian from which longitudes are measured.

• It is marked as 0° longitude.
• It passes through Greenwich in London, England.
• It is also called the Greenwich Meridian.
• It divides the Earth into the Eastern and Western Hemispheres.

Equator

The Equator is an imaginary circle around the middle of the Earth and represents 0° latitude.

• It is the longest parallel of latitude.
• It divides the Earth into the Northern Hemisphere and Southern Hemisphere.
• All other parallels of latitude are smaller than the Equator.

Hemispheres

A hemisphere means one half of the Earth.

• The Equator divides the Earth into the Northern Hemisphere and Southern Hemisphere.
• The Prime Meridian divides the Earth into the Eastern Hemisphere and Western Hemisphere.
• A place can belong to two hemispheres at the same time, such as the Northern and Eastern Hemispheres.

Latitude and Longitude Grid

Latitudes and longitudes together form a network of imaginary lines called a grid or grid lines.

• Parallels of latitude run from east to west.
• Meridians of longitude run from north to south, from pole to pole.
• The grid helps us locate any place precisely on the Earth.
• The approximate latitude and longitude of a place can be found using a globe or atlas.

Ancient Indian Knowledge of Latitude and Longitude

Ancient Indian astronomers were aware of the concepts of latitude, longitude and the need for a reference or prime meridian.

• Ujjayini, present-day Ujjain, was a reputed centre of astronomy.
• The ancient Indian prime meridian was called madhya rekhā, meaning the “middle line”.
• The Ujjayini meridian passed through Ujjayini.
• The Ujjayini meridian became a reference for calculations in Indian astronomical texts.
• Varāhamihira was a famous astronomer who lived and worked at Ujjayini about 1,500 years ago.

Location of India

India can be located precisely with the help of its latitudes and longitudes.

• India extends approximately from 8°N to 37°N latitudes.
• India extends approximately from 68°E to 97°E longitudes.
• India lies in the Northern Hemisphere.
• India also lies in the Eastern Hemisphere.

Earth's Rotation and Time

The Earth rotates on its axis, and this rotation causes differences in local time at different longitudes.

• The Earth completes one complete rotation of 360° in 24 hours.
• Therefore, the Earth rotates through 15° in one hour.
• Thus, a difference of 15° longitude corresponds approximately to a difference of one hour in local time.
• A difference of 1° longitude corresponds approximately to 4 minutes of time.

Longitude and Local Time

Local time at a place is related to its longitude.

• Places located towards the east have a later local time.
• Places located towards the west have an earlier local time.
• For every 15° difference in longitude, the local time differs by approximately one hour.
• For example, if it is noon at the Prime Meridian, the local time at 15°E is approximately 1 p.m.
• At 15°W, the local time would be approximately 11 a.m.

Local Time

Local time is the time calculated according to the longitude of a particular place.

• Different places can have different local times because they lie at different longitudes.
• As the Earth rotates from west to east, places to the east experience sunrise and later times earlier than places to the west.
• Using separate local times for every place in a large country would be inconvenient.

Standard Time

Standard time is an officially adopted time used throughout a country or a defined region.

• A country selects a particular meridian as the reference for its standard time.
• Standard time avoids confusion caused by different local times.
• India follows a single standard time called Indian Standard Time (IST).
• IST is based on the standard meridian of India.
• IST is 5 hours 30 minutes ahead of GMT.

Time Zones

A time zone is a geographical region in which the same standard time is followed.

• The Earth is divided broadly into time zones based on differences in longitude.
• A difference of approximately 15° longitude corresponds to one hour.
• Time-zone boundaries do not always exactly follow meridians of longitude.
• They may be adjusted to follow international or political boundaries.
• Large countries may have several time zones.
• The USA has six time zones.
• Russia has eleven time zones.

International Date Line

The International Date Line is an imaginary line located approximately at 180° longitude, opposite the Prime Meridian.

• The International Date Line is associated with a change of date.
• When the line is crossed while travelling eastward, one day is subtracted.
• When the line is crossed while travelling westward, one day is added.
• The line is approximately at 180° longitude rather than exactly following a straight meridian.
• It deviates in some places to avoid dividing countries into two different dates.

Important Differences

Important Numerical Relationships

• 360° rotation of Earth = 24 hours
• 15° longitude = 1 hour
• 1° longitude = 4 minutes
• Eastward movement = Add time
• Westward movement = Subtract time
• IST = GMT + 5 hours 30 minutes

Important Facts to Remember

• The Equator is the longest parallel of latitude.
• The South Pole is at 90°S.
• The Prime Meridian passes through Greenwich.
• Latitudes and longitudes together create a grid.
• Coordinates help us locate a place precisely.
• India follows Indian Standard Time.
• The International Date Line is approximately at 180° longitude.
• The date changes when the International Date Line is crossed.

All Topics Chapter Locating Places on the Earth

• 1. Chapter Review and Key Points
• 2. Notes
• 3. Assignments - What Have You Learned?