How does leap year occur? [V. Imp.]
The earth takes 36514 days Le. one year to complete one revolution around the sun. We consider a year as consisting of 365 days only and ignore six hours for our convenience. Six hours saved every year are added to make one day Le. 24 hours over a span of four years. This surplus day is added to the month of February. Thus every fourth year, February of 29 days instead of 28 days. Such a year with 366 days is called a leap year.
Fill in the blanks.
(a)A leap year has ………… number of days.
(b)The daily motion of the earth is ……… ……
(c)The earth travels around the sun in…………….
(d)The sun's rays fall vertically on the Tropice of…………….. on 21st June.
(e)Days are shorter during …………
Fill in the blanks with appropriate words to complete each sentence: .
(i) Days and nights occur due to …………… of the earth.
(ii) Only half of the earth gets light from the sun at a time due to its……………. shape.
(iii)The period of rotation is known as the ……………..
(iv) The sun's rays fall vertically at the Tropic of…………….. on 22nd December.
(v) On ………… it is autumn season in the Northern Hemisphere and spring in the Southern Hemisphere.
Explain the following with a diagram:
(a) Summer solstice (b) Winter solstice (c) Equinox.
Stale whether these sentences are true (T) or false (F).
(i) The axis of the earth makes an angle of 23V& with its orbital plane.
(ii) Every five year, February is of 29 days instead of 28 days.
(iii) Season changes due to the change in the position of the earth around the sun.
(iv) When there is summer in the Northern Hemisphere, it is spring in the Southern Hemisphere.
(v) Life is not possible in extreme conditions.
Answer the following questions briefly.
(a) What is the angle of inclination of the earth's axis with its orbital plane?
(b) Define rotation and revolution.
(c) What is a leap year?
(d) Differentiate between the summer solstice and winter solstice.
(e) What is an equinox?
(f) Why does the Southern Hemisphere experience winter and summer solstice in different times than that of the Northern Hemisphere?
(g) Why do the poles experience about six months day and six months night?