Maharashtra Board Class 6 Geography Chapter 1 The Earth and the Graticule PDF Download

The Earth and the Graticule

Make Friends With Maps!

Observe figure 1.1 and answer the following questions:

Which places are shown on the map?

In which city is the Taj Mahal located?

In which continent is the Taj Mahal located?

In which direction is the Taj Mahal located for Graham in St. Petersburg, for Katya in Kimberley, for Michiko in Tokyo and Minakshi in Port Blair?

Shahid in Agra is specifying the directions in which the others live. How will he express them?

In what direction will Natalia in Rome and Enrike in Lima say the other child lives? Will their answers be the same?

Graham, Katya, Michiko, Natalia, Minakshi, Shahid and Enrike have answered the above questions differently using directions and subdirections. The Taj Mahal is located at one and the same place and that is Agra. However, when each one of the children told the direction from their respective places, their answers were different. This means that the use of directions alone does not help us to accurately describe the location of a place. That is why, it became necessary to find a new system to state the precise location of any place on the earth.

Let us see what it is!

Teacher's Note

The Taj Mahal is in Agra. But from different cities, people see it in different directions. This is like when your home is north of your school, but south of your friend's house. Direction alone is not enough to find a place.

Exam Trick

Remember: One place cannot be in different directions at the same time! We need a better way to show location. That is why we use latitude and longitude - like an address number for places on Earth.

Points to Remember

Different people see the same place in different directions from their homes.
Direction words (north, south, east, west) are not enough to find a place on Earth.
We need a system that works the same way for everyone on Earth.
This system uses imaginary lines called latitude and longitude.

Figure 1.2 shows the lengths of the east-west and north-south diameters of the earth. This will give you some idea about the size of the earth. Oceanic waters, uneven nature of the land, forests, innumerable islands of different sizes, and buildings make it impossible to actually draw such lines on the earth. In order to overcome this difficulty, geographers developed a miniature model of the earth in the form of a globe. This can be used to determine locations on the earth. One can actually draw horizontal and vertical lines on a globe though not on the earth. Thus, they are imaginary lines on the earth.

Teacher's Note

A globe is a small copy of Earth. We can draw lines on it, but we cannot draw lines on the real Earth. These lines help us find any place on Earth easily.

Exam Trick

Remember: Lines on Earth are imaginary, not real. Just like how we draw a plan of a city on paper, we draw imaginary lines on Earth to find places.

Points to Remember

The Earth is very large and has oceans, mountains, and forests.
We cannot draw real lines on the Earth's surface.
A globe is a small model of the Earth where we can draw lines.
The lines on a globe and Earth are called imaginary lines.

Angular Distance

The location of any place on the earth is determined with reference to the centre of the earth. In order to do it, we consider a straight line joining the point on the surface and the centre of the earth. At the centre, it makes an angle with the plane of the equator. The measure of this angle is used in determining the locations. For example, in figure 1.3, the measure of angle XMV is 30°. That is, its angular distance from the equator is 30°. Look at the figure and tell the angular distance of 'Y' from the equator.

Figure 1.3 shows another plane. It passes through X. It is parallel to the plane of the equator. Observe 1.3 and see how it meets the surface of the earth. Note that it forms a circle on the surface. Any point on this circle and the equatorial plane form an angle of 30° at the centre of the earth.

Teacher's Note

Angular distance means the angle we measure from the center of Earth. If a place is 30 degrees away from the equator, we say its angular distance is 30 degrees. This is like measuring angles in geometry class.

Exam Trick

Remember: Angular distance is measured from the equator using angles at the center of Earth. The equator is 0 degrees, and the North and South Poles are 90 degrees each.

Points to Remember

Angular distance is the angle measured from Earth's center.
It tells us how far north or south a place is from the equator.
The equator is at 0 degrees angular distance.
Places 30 degrees from equator form a circle on Earth's surface.

Parallels of Latitude

You must have realized that the ellipse drawn by joining the 20° points is larger than the ellipse that joins the 60° points. However, the distances X K1 and X P2 are the same. This is because we are dealing with a sphere.

Note that though these lines appear to be ellipses in the diagram, on the globe they are circles. The circles thus created at some angular distance from the centre of the earth are parallel to one another. Hence, they are called parallels of these latitudes. The values of parallels are angular measures expressed in degrees.

The degrees of the parallels are measured from the equator as shown in figure 1.5. That is why, the equator is considered as 0° parallel. It is the largest parallel, and also a great circle. The angular distance of other parallels towards north and south goes on increasing away from the equator.

The equator bisects the earth into north and south parts. The one to the north is called the northern hemisphere while the one to the south is called the southern hemisphere. Towards the north and south of the equator, parallels of latitude progressively become smaller and smaller. On the globe (and also on the earth), at the north and south ends of the earth's axis, they appear as points. These are called the North Pole and the South Pole respectively.

While mentioning the value of a parallel, it is necessary to mention whether it is in the northern or southern hemisphere. The parallels from the northern hemisphere are referred to as 5°N, 15°N, 30°N, 50°N whereas the parallels from the southern hemisphere are referred to as 5°S, 15°S, 30°S, 50°S.

Teacher's Note

Parallels of latitude are like rings around Earth. The equator is the biggest ring at 0°. As we go north or south, the rings get smaller. Places on the same parallel have the same latitude.

Exam Trick

Remember: Latitude = "Lati" means width (like broad). Parallels of latitude are flat lines going east-west and are always parallel to each other. North parallels have N, South parallels have S.

Points to Remember

Parallels are circles on Earth that run east to west.
The equator is 0° and is the largest parallel.
Northern hemisphere has parallels marked N (like 30°N).
Southern hemisphere has parallels marked S (like 30°S).
All places on the same parallel have the same latitude.

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