The Earth also called Blue Planet. It is the densest of all planets.
Earth Circumference: 40,232 Kilometers.
Earth Area: 510 million Square Kilometers
Average distance from sun: 149 million Kilometers.
Earth Perihelion: Nearest position of earth to sun. The earth reaches its perihelion on January 3 every year at a distance of about 147 million-Kilometers.
Aphelion: Farthest position of earth from sun. The earth reaches its aphelion on July 4, when the earth is at a distance of 152 million Kilometers.
The shape of the earth is oblate spheroid or oblate ellipsoid (i.e. almost spherical, flattened a little at the poles with a slight bulge at the centre).
Types of Earth Movements:
1. Rotation or daily movement
2. Revolution or annual movement.
Earth Rotation
Spins on its imaginary axis from west to east in 23 hrs, 56 min & 40.91 sec.
Rotational velocity at equator is 1667 Kilometers/h & it decreases towards the poles, where it is zero.
Earth’s rotation results in
i. Causation of days & nights;
ii. A difference of one hour between two meridians which are 15° apart;
iii. Change in the direction of wind & ocean currents; Rise & fall of tides everyday.
iv. The longest day in North Hemisphere is June 21, while shortest day is on 22 Dec (Vice-versa in S.Hemisphere).
Days & nights are almost equal at the equator.
Earth Revolution
It is earth’s motion in elliptical orbit around the sun. Earth’s average orbital velocity is 29.79 Kilometers/s.
Takes 365 days, 5 hrs, 48 min & 45.51 sec. It results in one extra day every fourth year.
Revolution of the earth results in
i. Change of seasons
ii. Variation in the lengths of days & nights at different times of the year
iii. Shifting of wind belts
iv. Determination of latitudes
