Chapter 1 — Locating Places on the Earth

A map is a representation or drawing of some area, viewed from the top. It may show a small area like a village or town, a bigger area like a district or state, or a very large area like India or the whole world. An atlas is a book or collection of maps.

The three important components of maps are distance, direction, and symbols. Distance is shown using a scale; direction uses cardinal and intermediate points; symbols represent features such as roads, rivers, buildings, and natural elements in the limited space available on a map.

Scale shows how a distance on the map relates to the real distance on the ground. For example, a scale of 1 cm = 500 m means every centimetre on the map represents 500 metres on the ground. The actual distance between two points on a map depends on the scale being used.

The four cardinal directions are north, east, south, and west. The intermediate directions are northeast (NE), southeast (SE), southwest (SW), and northwest (NW). Most maps have an arrow marked with the letter 'N' pointing to the north direction.

There are three main kinds of maps: physical maps, which mainly show natural features such as mountains, oceans, and rivers; political maps, which show details of countries or states, boundaries, and cities; and thematic maps, which carry a specific kind of information.

Latitude measures the distance from the Equator towards one of the poles. Latitudes are expressed in degrees. The Equator is at 0°, while the North Pole is 90°N and the South Pole is 90°S. Lines of latitude (parallels) run east to west and are parallel to the Equator.

The Equator is an imaginary line halfway between the North Pole and the South Pole, and it is the largest parallel of latitude at 0°. The climate around the Equator is generally hot. As you travel away from the Equator towards the poles, the climate becomes more temperate and then frigid.

The Prime Meridian is the reference line for measuring longitude, marked as 0° longitude. In 1884, nations agreed that the meridian passing through Greenwich, an area of London in England, would become the international standard Prime Meridian. It is also called the Greenwich Meridian.

Coordinates are a pair of values — latitude and longitude — that together precisely identify the location of any place on Earth. For example, Delhi lies at approximately 29°N latitude and 77°E longitude. This system works like coordinates on a chessboard, where each square is fixed by a letter and a number.

The Earth rotates 360° in 24 hours, which means it turns 15° every hour. Moving eastward from the Prime Meridian by 15° adds one hour of local time; moving westward subtracts one hour. This is why the time of day differs around the world depending on longitude.

Indian Standard Time (IST) is the standard time used across India. It is 5 hours 30 minutes ahead of Greenwich Mean Time (GMT). India adopts a single standard time based on a meridian passing through the country rather than using many local times.

The International Date Line is located approximately at 180° longitude, opposite the Prime Meridian. If you cross it travelling eastward, you subtract a day; if you cross it travelling westward, you add a day. It deviates in places to avoid dividing some countries into two different calendar days.

India had its own prime meridian called the madhya rekhā, meaning 'middle line', which passed through the city of Ujjayinī (today called Ujjain). Varāhamihira, a famous astronomer, lived and worked there about 1,500 years ago. The Ujjayinī meridian became a reference for calculations in all Indian astronomical texts.

A globe is a sphere on which a map is drawn. Because the globe and the Earth share the same spherical shape, a globe represents the geography of the Earth more accurately than a flat map. Representing a sphere accurately on a flat sheet of paper is not possible — just as you cannot flatten orange peel without tearing it.

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