MOTIONS OF THE EARTH

Nicolaus copernicus

INTRODUCTION• The earth like all other planets of the

solar system has two kinds of motion.

• It spins in its own axis and goes

around the sun along a fixed path called as ORBIT.

• The spinning around its axis is called rotation and its movement is called as Rotation and its axis is known as Revolution

THE EARTH’S AXIS • It is an imaginary line joining the

north pole and the south pole.

• This axis is titled at an angle of 661/2 ˚ with the plane of the earth’s orbit or 231/2 ˚ with the vertical.

• This tilt is known as inclination of

the Earth’s surface

EFFECTS INCLINATION OF THE EARTH’S AXIS

• The inclination of the earth’s axis varying length of day and night.

• If it is vertical day and night would be in equal length through out the year.

• Because of inclination of the earth’s axis days and night are not same.

• In summer days are long and nights are short.

• In winter days are short and nights are long.

CIRCLE OF ILLUMINATION • It is an imaginary line which marks

the transition between the darkness and the illumination of the Earth’s surface

ROTATION

• The earth rotates from W to E and takes 24hours to complete one rotation.

• We consider this to be one day.

• This also called as daily motion of the earth

EFFECTS OF ROTATION

Formation of day and night

Deflection of winds and ocean

Flatting of the earth at poles and bulging at equator

Occurrence of tides twice a day

REVOLUTION

• The earth revolves around the sun in an anti clock wise direction.

• Its orbit is in elliptical in shape.

• The earth takes 365 days and 6 hours to complete one revolution.

EFFECTS OF ROTATION

Variation of day and night

Distribution of heat

Occurrence of season

OCCURRENCE OF SEASON

OCCURRENCE OF SEASON

The revolution of the earth

Inclination of the earth

SOLSTICE(standing still)Summer and Winter • 21 June - N.H inclined towards sun • Sun rays fall vertically on tropic of

cancer.• Days are longer and summer in N.H • 21st June is the longest day.

• Opposite in S.H • Days are shorter hence winter in S.H

• 22 December - S.H inclined towards sun • Sun rays fall vertically on tropic of

Capricorn.• Days are longer and summer in S.H

• Opposite in N.H • Days are shorter hence winter in N.H

EQUINOX

• 21 March – on this date the sun shines vertically over the equator.

• All the places in equator will have

equal day and equal night.

• The N.H has spring • The S.H will have autumn

• 21 March is called as spring or vernal

• 23 September - on this date the sun shines vertically over the equator.

• All the places in equator will have equal day and equal night.

• The S.H has spring • The N.H will have autumn.