Motions of the earth

                                Motions of the earth

Earth has two types of motions 

Rotation-movement of the earth on its axis
Day and Night 

Revolution-Movement of the earth around the sun in a fixed path or orbit.
 It takes 365 ¼ days(one year)

Earth day-Period of rotation is known as the earth day.

Orbital plane-The plane formed by the orbit is called orbital plane.

Axis of the earth makes an angle of 66 ½ degree with its orbital plane.

Circle of illumination-The circle that divides the day from night on the globe is called circle of illumination

Leap yearEvery fourth year, when the month of February have 29 days instead of 28 then that year is known as leap year.

Earth moves around the earth in elliptical orbit

Season change-Seasons change  is due to the change in the position of the earth around the sun.

Summer solstice-21st june

On 21 june,the Northern Hemisphere is tilted toward the sun .On the Tropic of cancer rays of the sun falls directly due to this ,these area receives more heat.The area near the poles receives less heat as the rays of the sun are slanting.

Large portion of the northern hemisphere is getting light from the sun therefore it is summer in the regions north of the equator.

Revolution of the earth and seasons

Summer solstice-21 june 

Northern Hemisphere
  • On 21 june it is the longest day and shortest night.
  • It is the summer season in the northern hemisphere on 21 june

Southern Hemisphere
  • On 21 june  nights are longer than days in the southern Hemisphere
  • It is the winter season in the southern Hemisphere.

Winter solstice-22nd December
On 22nd December ,the tropic of Capricorn receives direct rays of the sun as the south pole tilts towards it.  Larger portion of Southern hemisphere gets lights therefore it is summer season in the northern hemisphere.]
summer solstice,winter solstice and equinox

Winter Solstice

Northern Hemisphere
  • Shorter days and longer nights in northern Hemisphere
  • It is the winter season

Southern Hemisphere
  • Longer days and shorter night in the southern hemisphere.
  • It is the summer season in the southern hemisphere.

Equinox-equal days and equal nights(21st March and September 23rd)

On 21st March and September 23rd  rays of the sun fall direct on the equator .At this position neither of the poles is tilted toward the sun. So the whole earth experiences equal days and equal nights this is called an equinox.

On 21st March
Northern Hemisphere-Spring season
Southern Hemisphere-Autumn season

On 23rd September
Northern Hemisphere- Autumn season
Southern Hemisphere- Spring season

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