15 worked answers · short steps first, explanations when you need them
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Textbook pages chapter end
Question 1
In Fig. 12.17, how many hours of sunlight do the North Pole and South Pole receive during one rotation of Earth?
Steps only
In the figure, the North Pole is in darkness and the South Pole is in sunlight.
Answer
North Pole: 0 h sunlight; South Pole: 24 h.
Question 2
Fill in the blanks: (i) Stars rise in the ___ and set in the ___. (ii) Day and night are caused by Earth’s ___. (iii) When the Moon fully covers the Sun from our view, it is called a ___ solar eclipse.
Steps only
Recall Earth’s rotation and the names of eclipse types.
Answer
(i) East, West
(ii) rotation
(iii) total
Question 3
State True or False: (i) A lunar eclipse occurs when the Sun comes between Earth and Moon. (ii) Sunrise happens earlier in Gujarat than in Jharkhand. (iii) Chennai’s longest day occurs on the summer solstice. (iv) It is safe to watch a solar eclipse directly with the naked eye. (v) Seasons occur due to Earth’s axial tilt and spherical shape. (vi) Earth’s revolution around the Sun causes day and night.
Steps only
Check eclipse alignment, east–west location, axial tilt, and rotation.
Answer
(i) F
(ii) F
(iii) T
(iv) F
(v) T
(vi) F
Question 4
Padmashree saw Orion nearly overhead at 8 pm yesterday. When will she see Orion overhead today?
Steps only
A star appears about 4 minutes earlier each day.
Answer
About 7:56 pm today.
Question 5
Nandhini saw a group of stars rising at midnight on 21 June. When will she see the same group rising at midnight next year?
Steps only
The yearly change adds up to about 24 hours.
Answer
Around midnight on 21 June next year.
Question 6
Why is it daytime in India while an uncle in the USA may be sleeping at night?
Steps only
Earth’s rotation gives places at different longitudes different local times.
Answer
India and the USA are turned toward and away from the Sun at different times.
Question 7
Which friend is careless: Ravikiran uses solar-eclipse goggles; Jyothi uses a mirror to project the Sun’s image; Adithya looks directly at the Sun; Aruna attends a planetarium programme?
Steps only
Never look directly at the Sun.
Answer
Adithya is careless.
Question 8
Label the circles in the figure with Sun, Moon, and Earth.
Steps only
Solar: Sun–Moon–Earth. Lunar: Sun–Earth–Moon.
Answer
Solar row: Moon, Earth. Lunar row: Sun, Earth.
Question 9
The Moon is much smaller than the Sun. How can it block the Sun completely during a total solar eclipse?
Steps only
The nearby Moon and distant Sun appear nearly the same size.
Answer
The Moon can cover the Sun because it is much closer to Earth.
Question 10
Indian cricket matches in Australia are often held in December. Should the team pack winter or summer clothes?
Steps only
December is summer in the Southern Hemisphere.
Answer
Summer clothes.
Question 11
Why can a lunar eclipse be seen from a large part of Earth, while a total solar eclipse is seen from only a small part?
Steps only
Earth’s night side is wide; the Moon’s total shadow on Earth is a narrow strip.
Answer
Lunar eclipses are visible across a wide area; solar totality is limited to a small path.
Question 12
If Earth’s axis were not tilted compared with its orbital plane, what would happen to the seasons?
Steps only
Without tilt, yearly changes in sunlight between the hemispheres would be much smaller.
Answer
There would be no pronounced tilt-driven seasons.
Exploratory Projects
Textbook pages chapter end
Question Project 1
Use a lamp and tilted globe to compare illumination and day length in the two hemispheres at different positions around the lamp.
Steps only
Keep the axis tilted the same way; compare light and day length at each orbit position.
Answer
The hemisphere tilted toward the lamp receives longer days and more direct light.
Question Project 2
Draw circles of radius 14.7 cm and 15.2 cm using the given scale. What distance difference do they represent?
Steps only
Multiply each radius by 10 million km per cm; subtract the results.
Answer
147 million km and 152 million km; difference = 5 million km.
Question Project 3
Would a larger Earth-axis tilt cause more extreme seasons? Compare Earth’s tilt with Uranus and write a short article.
Steps only
Greater tilt means stronger seasonal sunlight changes; Uranus’s tilt is about 98°.