Grade-6, Social Science, Worksheet - Rotation and Revolution

 

Rotation and Revolution

Study the diagram given below and fill in the table:

Position	Description
A	Summer Solstice- The North Pole is tilted towards the sun. The overhead or direct rays of sun fall on the Tropic of Cancer. Northern hemisphere has the summer season with 21st June being the longest day (longer days and shorter nights).  The region between the Arctic circle and the North pole has a period of only daylight and no night.  Southern hemisphere experiences winter and days are shorter and nights are longer.
B	Autumnal Equinox (three months after summer solstice) - Overhead rays are in transition from the northern hemisphere to southern hemisphere. Overhead on the equator. Entire earth has day and night of equal duration. It occurs around 23rd September.
C	Winter solstice (six months after summer solstice)- South pole is tilted towards the sun and the overhead rays of the sun are falling on the Tropic of Capricorn. Southern hemisphere has a summer season with 22nd December being the longest day. (longer days and shorter nights). Places of the Antarctic Circle experience only daylight and no light. Northern hemisphere has shorter days and longer nights.
D	Vernal Equinox/Spring (three months after winter solstice) - Overhead rays are once again on the equator but their transition is from southern hemisphere to northern hemisphere. It occurs on 21st March.

Fill in the blanks:

1) One rotation of the earth on its axis takes about 24 hours.

2) The journey of the earth around the sun in an eliptical orbit.

3) The seasons are opposite in the two hemispheres.

4) A leap year has 366 days.

5) The circle that separates day and night on the Earth is called

the circle of illumination.

Match the following:

A	B
Summer solstice	21st June
Winter solstice	22nd December
Vernal equinox	21st March
Autumnal equinox	23rd September

3. Define:

a) Leap Year

Revolution of earth around sun in an eliptical orbit takes 364 ¼ days. 

¼ day is equal to 6 hours. This 1/4th day of four consecutive years is added to make one full day. This one full day is added to the month of february in the fourth day. 

Thus every fourth day has 366 days. The month of february has 29 days in this year. Such a year is called a leap year.

b) Solstice

Either of the two moments in the year when the Sun’s apparent path is farthest north or south from Earth’s Equator is called solstice. 

At the time of the summer solstice in the Northern Hemisphere, the North Pole is tilted about 23.4° (23°27´) toward the Sun. The vertical noon rays are directly overhead at the Tropic of Cancer (23°27´ N).

At the time of the winter solstice in the Northern Hemisphere, the South Pole is inclined about 23.4° toward the Sun. The vertical noon rays are directly overhead at the Tropic of Capricon (23°27´ S).

c) Equinox- 

One of the two days in a year when the direct rays of the sun fall on the equator causing equal day and night all over the globe. 

Autumnal equinox- 23rd September

Spring or vernal equinox - 21 March