Latitudes and Longitudes
India lies entirely to the north of the Equator, between latitudes 8°-4´ and 37°-6´ north and longitude 68°-7´ and 97°-25´ east.
The latitude of the South Pole is 90°. South Pole has no longitude.
Longitude of a place is its distance east or west of a fixed meridian. The distance of any place north or south of the Equator is called the Latitude of that place.
Parallels of latitude: are lines drawn on a map (or globe) showing the latitude of a place.
Meridians (or lines) of longitude: These are lines drawn on a map (or globe) showing the longitude of a place. These lines join the north and south pole cutting the Equator at right angles.
(Latitudes and Longitudes should be clearly distinguished from Parallels of Latitude and Meridians of Longitude respectively.)
By knowing these lines, we can find out exact location of a place. By knowing the latitude of a place we can find out its average temperature, as also its distance from the Equator. By knowing the longitude of a place, we can calculate its local time.
Longitude is the angular distance of a place east or west of the prime meridian. The earth rotates upon its axis once in 24 hours and covers 360° in 24 hours. Thus it takes 60 x 24/360 or 4 minutes to cover a degree of longitude or we may say that in four minutes, the earth moves through 1°. There is thus a difference of 4 minutes for each degree of longitude. This fact is used for determining the longitude of a place. All longitudes are measured from the meridian of Greenwich.
We can determine the latitude of a place in the northern hemisphere by measuring the altitude of the Pole Star. The altitude of the Pole Star is the latitude of that place. For example, if the altitude of Pole Star at Delhi is 28.5° North, its latitude will also be 28.5°N. The altitude of Pole Star is measured by an instrument called Sextant.