This ppt is on motions of earth which is useful for cl vi,cbse. The meaning of some key words are written in regional language(odia) to help the children of my school for better understanding. Hope it will help you.

1. MOTIONS OF THE EARTH (ପୃଥିବୀ ର
ଗତି )
PREPARED BY : NANDITA SINGH
. .
T.G.T(SO.SC.)
J N V ,PURI

2. ROTATION (ଆବର୍ତ୍ତନ)
• Rotation is the movement(ଚଳନ ) of the Earth on its axis.(ଅକ୍ଷ )
• Earth takes about 24 hours to complete one rotation around its axis.
• The period of rotation is called Earth day.
• This is the daily motion of the earth.
• Due to rotation day and night takes place.

3. REVOLUTION(ପରିକ୍ରମଣ )
• The movement of earth around the sun in a fixed path or
orbit(କକ୍ଷ ) is called revolution.
• Earth takes about 365 and one fourth days or 365 or six hours
to revolve(ବୁଲିବାକୁ ) around the sun.

4. WHAT WOULD HAPPEN IF THE EARTH DOES NOT
ROTATE OR REVOLVE
• If the earth does not rotate the portion of the Earth facing the sun would
always experience day.
• The other half would remain in darkness and experience freezing cold all the
time .so life would not have been possible in either area for extreme(ଅତିଶୟ )
temperature.
• If the earth does not revolve there will not be change of season.

5. INCLINATION(ଢଳିବା ) OF EARTH’S AXIS AND
ORBITAL PLANE(କକ୍ଷ ପୃଷ୍ଠ )
• The axis of the Earth which is an imaginary line makes an angle(କକାଣ )
of 66 ½ degree with its orbital plane.
• The plane formed by the orbit is known as the orbital plane(କକ୍ଷ ପୃଷ୍ଠ )

6. CIRCLE OF ILLUMINATION(ଆକଲାକନ ବୃର୍ତ୍
)
• The earth receives light from the sun. Due to the spherical(ବର୍ତ୍ତୁ ଲାକୃତି) shape of
Earth only half of its get light from the sun at a time.
• The portion facing the sun experience day while the other half away from the
sun experiences night.
• The circle that divides the day from the night on the globe is called the circle
of illumination.

7. LEAP YEAR(ଅଧି ବର୍ତ )
• Earth takes 365 and 6 hours to revolve around the sun.
• But we consider a year as 365 days and ignore 6 hours for our
convenience.(ସୁବିଧା କ ାଗୁ)
• This 6 hours saved every year and added to make 24 hours or one
day over a period of four years.
• This surplus(ବଳକା) day is added to the month of February .
• Thus in every fourth year February has 29 days instead(ପରିବକର୍ତ୍ତ )of 28
days and the year has 366 days instead of 365 days.
• Such a year is called leap year.

8. CHANGE OF SEASON.
• Earth moves around the sun in an elliptical (ପ୍ରଲମ୍ବିତ )orbit
• Notice(ଲକ୍ଷ୍ୟ କର) throughout its orbit the earth is inclined in the same
direction.
• Year is usually divided into summer ,winter, spring and autumn seasons.
seasons change due to change in the position of the earth around the sun.

9. SOLSTICE(ଅୟନାନ୍ତ )

11. SUMMER SOLSTICE (ଗ୍ରୀର୍ମ
ଅୟନାନ୍ତ)
• On 21st june the northern hemisphere is tilted towards the sun.
• The rays of sun fall directly on the tropic of Cancer(କକତଟ କ୍ରାନ୍ତି) as a result
these areas receives more heat.
• During this time the northern hemisphere experiences summer season. In
summer the days are longer and the nights are shorter.
• At this time in the southern hemisphere the condition is just reversed.
• At this time the southern hemisphere experiences winter season the
nights are longer and the days are shorter.
• This position of earth is called the summer solstice.

12. WINTER SOLSTICE (ଶୀତ ଅୟନାନ୍ତ )
• On 22nd December the tropic of Capricorn(ମକର କ୍ରାନ୍ତି) receives direct rays of
the sun and the southern hemisphere remained tilted towards it.
• During this time the southern hemisphere experiences summer season. The
days are longer and the nights are shorter.
• At the same time the northern hemisphere experiences winter season. The
days are shorter and nights are longer.
• This position of earth is called Winter solstice..
• As Australia is situated in southern hemisphere. so in Australia ,Christmas is
celebrated in the summer season.

13. EQUINOX(ସମ ଦିଵରାତ୍ରୀ ଦିବସ )
• On 21st March and 23rd September direct rays of the sun fall on the
equator.(ବିର୍ୁବ କରଖା)
• At this position neither of the poles is tilted towards the sun. so the
whole Earth experiences equal days and equal nights. This position
of earth is called equinox.
• On 23rd September it is autumn season in the northern hemisphere
and spring season in the southern hemisphere
• On 21st March it is spring season in the northern hemisphere and the
autumn season in the southern hemisphere.