Chapter 12 Solutions — Earth, Moon and the Sun

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1. 1.
   In Fig. 12.17, how many hours of sunlight do the North Pole and the South Pole receive during one rotation of the Earth?
2. 2.
   Fill in the blanks:

   • (i) Stars rise in the _________ and set in the ___________.
   • (ii) Day and night are caused by the Earth's ________________.
   • (iii) When the Moon fully covers the Sun from our view, it is called a _____________ solar eclipse.
3. 3.
   State whether True or False:

   • (i) Lunar eclipse occurs when the Sun comes between the Earth and the Moon.
   • (ii) Sunrise happens earlier in Gujarat than in Jharkhand.
   • (iii) In Chennai, the longest day occurs on the summer solstice.
   • (iv) We should watch the solar eclipse directly with our naked eye.
   • (v) Seasons occur due to the tilt of Earth's axis of rotation and its spherical shape.
   • (vi) The…
4. 4.
   Padmashree saw the Orion constellation nearly overhead at 8 pm yesterday. When will she see Orion overhead today?
5. 5.
   Nandhini saw a group of stars rising at midnight on 21 June. When will she see the same group of stars rising at midnight next year?
6. 6.
   Abhay noticed that when it was daytime in India, his uncle who was in the USA was generally sleeping as it was night-time there. What is the reason behind this difference?
7. 7.
   Four friends used the following ways to see the solar eclipse. Who among them was being careless?

   • (i) Ravikiran used a solar eclipse goggle.
   • (ii) Jyothi used a mirror to project the Sun's image.
   • (iii) Adithya saw the Sun directly with his eyes.
   • (iv) Aruna attended a programme arranged by a planetarium.
8. 8.
   Fill in the circles in Fig. 12.18 appropriately with one of the following: Sun, Moon, Earth. (The figure shows the geometry of a solar eclipse and a lunar eclipse, with one circle already filled as 'Sun' in solar eclipse and 'Moon' in lunar eclipse.)
9. 9.
   The Moon is much smaller than the Sun, yet it can block the Sun completely from our view during a total solar eclipse. Why is it possible?
10. 10.
    The Indian cricket team matches in Australia are often held in December. Should they pack winter or summer clothes for their trip?
11. 11.
    Why do you think lunar eclipses can be seen from a large part of the Earth when they happen, but total solar eclipse can be seen by only a small part of the Earth?
12. 12.
    If the Earth's axis were not tilted with respect to the axis of revolution, explain what would be the effect on seasons?