Motions of the Earth

Motions Of The Earth: The Earth is constantly in motion, revolving around the Sun and rotating on its axis. These motions account for many of the phenomenon we se as normal occurrences: night and day, changing of the seasons, and different climates in different regions. With a globe ball properly mounted and rotating on its axis, the movements of the Earth around the Sun may be illustrated accurately.

Rotation: The Earth spins on its axis from West to East (counter-clockwise). It takes the Earth 23 hours, 56 minutes, and 4.09 seconds to complete one full turn. Day and night are produced by the rotation of the Earth. The speed of rotation at any point upon the equator is at the rate of approximately 1,035 miles per hour, decreasing to zero at the poles.

Revolution: While the Earth is spinning on its axis, it is revolving around the Sun in a counter-clockwise direction. The mean distance of the Earth from the Sun is about 93 million miles (150 million km) and the distance varies by 3 million miles, forming a slightly oval path. In its revolution around the Sun, Earth traverses a distance of 595 million miles in 365 days, 6 hours, 9 minutes and 9.5 seconds. This means a speed of 18 miles a second or 66,000 miles per hour (107,000 km/hr), while at the same time rotating once each set of twenty-four hours. Revolution causes unequal days and seasons on earth.Among other motions of Earth is precession or wobbling (like a spinning top) caused by the gravitational attraction of the sun and the moon.

Location Of A Place And Time On Surface Of The Earth: Any location on Earth is described by - its latitude and its longitude. Latitude and longitude are angles that uniquely define points on a sphere. They are spherical coordinates on the surface of the earth.

Latitude: Halfway between the North Pole and the South Pole is an imaginary line, the equator. The equator goes around the middle of Earth like a belt. It divides our planet into the Northern Hemisphere and the Southern Hemisphere. A number of imaginary lines are drawn around the globe parallel to the equator. These are called parallels of latitude. Latitude is measured North or South of the Equator, resulting in a range of -90 (S pole) to +90 (N pole) degrees. Each degree of latitude spans about 111 km or60 nautical miles on the earth's surface. Each degree is divided into 60 min and each min into 60 sec

Longitude: Another set of imaginary lines helps us measure distance between east and west. These are lines of longitude, Each line of longitude runs from the North Pole to the South Pole. These lines are also called meridians. Meridians are spaced farthest apart at the Equator and converge at the poles. Longitude is measured East or West of Greenwich. The International Date Line is 180° from the Greenwich Mean Time. Halfway around the Earth is 180 degree longitude. Longitude is an important factor in determining time in all parts of the world. Time alters by one hour for every 15 degrees of longitude (360/24). Time Zones am decided on the basis of meridians. Indian Standard Time, for example, is based on the local time at Allahabad at 82.5° E.

Then there are other imaginary lines apart from the longitude and the latitude. Arctic Circle runs parallel to the Equator and circles the Earth at about 66° 33' North Latitude. Antarctic Circle runs parallel to the Equator and circles the Earth at about 66° 33' South Latitude. Tropics of Cancer and Capricorn are the regions ol Earth between the Tropic of Cancer (23° 27 N) and Tropic of Capricorn (23° 27'S).

Chapters

Pre-Historic Period

Indus Valley Civilization

Vedic Civilization

Religious Reform Movement

The Early Kingdoms

The Mauryan Empire

Post Mauryan Period

The Age Of The Guptas

Post Gupta Era

Age of Rajput

Khilji Dynasty