The Earth is an oblate spheroid. It is almost spherical, flattened a little at the poles with a slight bulge at the centre (equator).
Perihelion Nearest position of the Earth to the Sun
Aphelion Farthest position of the Earth to the Sun
The Earth’s interior is composed of three major layers: the crust the mantle and the core.
Eduard Suess has explained the interior of Earth on the basis of chemical composition as SIAL, SIMA and NIFE.
SIAL (Silicon-Aluminiu) Upper part of the crust.
SIMA (Silicon-Magnesium) Lower part of the crust.
NIFE (Nickel-Iron) Outer part of the core.
Rotation of the Earth – Earth spins on its imaginary axis from West to East in one day Result in causation of day and night, tides.
Revolution of the Earth – Earth’s motion in elliptical orbit around the Sun one year. Result in Change of Seasons.