The Earth

  • The Earth
  • Also called Blue Planet. It is the densest of all planets.
  • Circumference: 40,232 km. Area: 510 million sq. km. Average distance from sun:149 million-km.
  • Perihelion: Nearest position of earth to sun. The earth reaches its perihelion on January 3 every year at a distance of about 147 million-km.
  • 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 km.
  • The shape of the earth is oblate spheroid or ablate ellipsoid (i.e. almost spherical, flat tended a little at the poles with a slight bulge at the centre).
  • The earth has two motions:
  • Rotation of the Earth
  • It turns around its own axis once is Hrs. 56 Min and 4.09 S(24 hours) from West to East.
  • Revolution of the Earth
  • It revolves around the sun in about 365 days, 5 Hrs., 48 min and 45.51 s
  • Effect of Rotation: Days and nights are caused. The sun, the moon and other heavenly bodies appear to revolve round the earth from East to West direction of winds and currents is changed.
  • Effect of Revolution: It causes seasons, day and nights are of unequal length at the same place.

      The earth can be divided roughly into three zones:

  • The Torrid Zone: It lies between the Tropic of Cancer and the Tropic of Capricorn, i.e.,  North and South on either side of the Equator. It is the hottest zone, where vertical rays of the sun are received.
  • The Temperature zone: It is between the Torrid and the Frigid zone  North and South on either side of the equator. It never receives vertical rays.
  • The Frigid Zone: It lies between  and the poles in the Northern and Southern Hemispheres. It is the coldest zone from which the sun’s rays are excluded entirely atleast for one whole day in a year.