Motions Of The Earth
|Four Seasons as seen from Northern Hemisphere|
NCERT Chapter Q & A and Other Short Questions and Answers
Q1: What is the angle of inclination of the earth’s axis with its orbital plane?
Answer: The angle of inclination of the earth's axis with its orbital plane is 66½°
Q2: Define rotation and revolution.
Answer: Rotation: It is the movement of the earth on its axis.
Revolution: It is the movement of the earth around the sun it its orbit.
Q3: Name the two movements of the earth.
Answer: Rotation and Revolution.
Q4: The Earth moves like a spinning top. What is this movement called? What does it result in?
Answer: It is called rotation. It results in formation of day and night.
Q5: In which direction the earth rotates? How much time does it take complete one rotation?
Answer: West to East. It takes 24 hours to complete one rotation.
Q6: What would happen if the earth did not rotate?
Answer: The portion of the earth facing the sun would always experience day. It would continuously warm that region. The other half would remain in darkness and would freeze in cold. Lives of animals and plants would not sustain in such harsh conditions.
Q7: What is a leap year?
Answer: The earth takes 365 Days and 6 hours to complete its revolution. For the sake of convenience a calendar year is considered to be equal to 365 days. Every fourth year (i.e. 6 Hours x 4 = 24 Hours) and extra day is added. Such a year of 366 days is called Leap Year.
Q8: In which direction does the earth revolve? (clockwise or anti-clockwise)
Q9: What is circle of illumination? Does it match the earth's pole to pole axis?
Answer: The circle that divides the day from night on the globe is called the circle of illumination. No it does not match with the earth's pole to pole axis.
Q10: Differentiate between the Summer and Winter Solstice.
|Summer Solstice||Winter Solstice|
|1.||North Pole is tilted towards the Sun.||North Pole is way from the Sun.|
|2.||The Sun rays fall directly on the Tropic of Cancer.||The Sun rays fall directly on the Tropic of Capricorn.|
|3.||Northern Hemisphere has longer days and shorter nights.||Southern Hemisphere has longer days and shorter nights.|
|4.||North Pole remains in day light whole day (June 21).||South Pole remains in day light whole day (December 22).|
Q11: What is the shape of the orbit in which the earth revolves around the Sun?
Answer: Elliptical orbit.
Q12: What is an equinox?
Answer: When days and nights are equal on the earth it is known as equinox. March 20 and September 23 are two equinox days in a year. At Equinox day, rays of the Sun is perpendicular to the equator as a result both hemispheres receive equal sun light.
Q13: Name the four major seasons. What causes the change of seasons?
Answer: Summer, winter, spring and autumn are the four major seasons. Seasons change due to the change in the position of the earth around the sun.
Q14: In which month the earth is nearest to the Sun?
Q15: In which month the earth is nearest to the Sun?
Q16: Can we say the in July the earth is nearest to the Sun, that's why we experience summer in India?
Answer: No. Seasons are formed due to tilted axis of the earth. In July the Northern Hemisphere receives maximum sunlight and experiences summer. At the same time, the southern hemisphere receives is tilted away from the sun and receives less sunlight. It experiences winter at that time.
Q17: Why does the Southern Hemisphere experience Winter and Summer Solstice in different times than that of the Northern Hemisphere?
Answer: When the North Pole is tilted towards the Sun, the Sun rays fall vertically overhead at Tropic of Cancer. Northern hemisphere receives more sun light and heat. Thus it experiences summer. At the same time, the South Pole is away from the sun and the Southern hemisphere receives very less sun light. Here days are shorter and nights are longer. Thus the Southern Hemisphere experiences winter at that time.
Similarly when the North Pole is away from the Sun, at that time the South Pole is inclined towards the Sun. Thus at that time, the Northern hemisphere experiences winter while the Southern hemisphere sees summer.
Q18: Why do the poles experience about six months day and six months night?
Answer: Due to the Earth's tilted axis, each pole receives continuous sun light for six months and thus experience six months day and night. For six months (June onwards), the North pole is inclined towards the sun and receives sun light through the day. It experiences six months day. At the same time, the south pole is way from the sun and receives very less or no sunlight. Thus the south pole sees six months night. After six months (December onwards), the positions are reversed.
Q19: Tick the correct answers.
(a) The movement of the earth around the sun is known as
Answer: (ii) Revolution
(b) Direct rays of the sun fall on the equator on
(i) 21 March
(ii) 21 June
(iii) 22 December
Answer: (i) 21 March
(c) Christmas is celebrated in summer in
Answer: (iii) Australia
(d) Cycle of the seasons is caused due to
Answer: (ii) Revolution
Q20: 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 ______________ orbit.
(d) The sun’s rays fall vertically on the Tropic of ___________ on 21st June.
(e) Days are shorter during ___________ season.