Class 6 Social Science Chapter 1: Locating Places on the Earth Notes

Why do we need maps?

The chapter opens with words of the astronomer Āryabhaṭa (about 500 CE), who described the Earth as a globe standing in space. Then it asks a practical question: if you visit a city for the first time, how do you find the places you want to see? You could ask someone, or you could look at a map. The book’s map of an imaginary small city lets you plan a route from the railway station to the bank, find the school, the public garden and the museum, and walk on from the bank to the market.

A map is a representation, or drawing, of an area as if you were looking at it from the top. The area can be small (a village or town), bigger (a district or State) or very large (India or the whole world). An atlas is a book or collection of maps. There are several kinds:

Kind of map	What it mainly shows
Physical map	Natural features: mountains, oceans, rivers
Political map	Countries or States, boundaries, cities and capitals
Thematic map	One specific kind of information

The three components of a map

Every map is built on three components: distance, direction and symbols. Read more in components of a map.

Distance and scale. A huge area fits on a small sheet thanks to the map’s scale. If each centimetre on the city map stands for 500 metres on the ground, the scale is 1 cm = 500 m. On the book’s map of India in Chapter 5, a small ruler 2.5 cm long stands for 500 km.

Direction. North is at the top of most maps; moving clockwise come east, south and west. These four are the cardinal directions. Between them lie the intermediate directions: northeast (NE), southeast (SE), southwest (SW) and northwest (NW). Most maps just show an arrow marked N.

Symbols. There is no room to draw every building on the map of a large city or a country, so symbols stand for railway lines, roads, boundaries, rivers, wells, tanks, bridges, places of worship, post offices, police stations, trees and more. In India, the Survey of India, a government body, fixes a standard set of symbols so that everyone reads maps the same way.

Mapping the Earth: the globe

The Earth is not flat. It is nearly a sphere, slightly flattened at the poles. A sphere cannot be shown accurately on flat paper: try flattening three or four large pieces of orange peel on a table and they tear at the edges. A globe is a sphere on which a map is drawn, so it shows the Earth’s shape truly.

Coordinates: latitude and longitude

To tell a friend where to meet in a market with neat rows of shops, you might say “the 7th shop in the 5th row from the entrance”. A chessboard works the same way: columns a to h and rows 1 to 8 name every square, so a pawn moving from d2 to d4 is recorded exactly. Two values that fix a place are called coordinates. On the Earth, they are latitude and longitude.

Latitudes. The Equator circles the globe halfway between the North and South Poles. Latitude measures how far a place is from the Equator: 0° at the Equator, up to 90°N and 90°S at the poles. An east–west line through any point is a parallel of latitude; the Equator is the longest, and the parallels get smaller towards the poles. Latitude is linked to climate: hot (torrid) near the Equator, moderate (temperate) farther away, and cold (frigid) near the poles.

Longitudes. Meridians of longitude are half-circles from pole to pole. In 1884, nations chose the meridian through Greenwich, in London, as the Prime Meridian (0°). Longitude measures distance east or west of it, from 0° to 180°E or 180°W. In round figures, New York is at 74°W, Delhi at 77°E and Tokyo at 140°E. Because 180°E and 180°W are the same line, it is written simply as 180°.

Together, parallels and meridians form a grid, and any place can be located by its two coordinates: Delhi lies at about 29°N latitude and 77°E longitude. The Equator divides the Earth into the Northern and Southern Hemispheres; the Prime Meridian divides it into the Western and Eastern Hemispheres. India lies roughly between 8°N and 37°N, and between 68°E and 97°E. Long before Greenwich, India had a prime meridian of its own, the madhya rekhā through Ujjayinī (Ujjain). Read more in latitudes and longitudes.

Local time, standard time and time zones

The Earth spins from west to east, making a full turn of 360° in about 24 hours: 15° every hour, or 1° every 4 minutes. If it is 12 noon at Greenwich, the local time is 1 pm at 15°E and 11 am at 15°W. That is why the sun has already set in Tinsukia (Assam) while it is still daylight in Porbandar (Gujarat), about 30° farther west.

Many local times in one country would be confusing, so most countries follow one standard time. Indian Standard Time (IST) is 5 hours 30 minutes ahead of Greenwich Mean Time (GMT). Time zones roughly follow 15° bands but bend along borders; large countries have several, the USA six and Russia eleven. Opposite the Prime Meridian, at about 180°, runs the International Date Line: cross it eastward and you subtract a day, cross it westward and you add one. Read more in Indian Standard Time.

Answers to every question in the chapter are in the NCERT solutions for Chapter 1.