TEXTBOOK SOLUTIONS & EXTRA PRACTICE
Chapter 3: Rotation and Revolution
II. Answer the following questions briefly
1. What is the name given to the path along which the Earth travels when moving round the Sun?
How long does this movement take?
• Path: Elliptical orbit.
• Duration: 365¼ days (365 days and 6 hours).
2. Name an effect of the Earth's rotation.
• Alternation of day and night.
3. State two effects of West-to-East rotation of the Earth.
• The Sun, Moon, and stars appear to rise in the east and set in the west.
• Difference in local time between different places on Earth (4 minutes for every degree of longitude).
4. What causes light flattening of the Earth at the two poles?
• The centrifugal force generated by the speed of Earth's rotation.
5. What is a leap year?
• A year having 366 days (with February having 29 days) occurring once every four years to adjust for
the accumulated extra ¼ day (6 hours × 4 = 24 hours) of Earth's revolution.
6. What is meant by the inclination of the Earth's axis? What are its two main effects?
• Meaning: The tilt of the Earth's axis at an angle of 23½° from the vertical (66½° to the orbital plane).
• Two main effects:
1. Variation in the length of day and night throughout the year.
2. Occurrence and changing of seasons.
7. Define briefly the following terms and mention the dates on which these are experienced:
• (a) Solstice: The position when the Sun is directly overhead at one of the tropics.
Dates: Summer Solstice (21 June), Winter Solstice (22 December).
• (b) Equinox: The position when the Sun is vertically overhead at the Equator, resulting in equal day
and night.
Dates: Vernal Equinox (21 March), Autumnal Equinox (23 September).
• (c) Aphelion: The position where Earth is farthest from the Sun (≈ 152 million km).
Date: 4 July.
• (d) Perihelion: The position where Earth is closest to the Sun (≈ 147 million km).
Date: 3 January.
8. Explain fully the meaning of the term 'Equinox'.
• Derived from Latin meaning equal night. On these days (21 March and 23 September), the Sun's rays
fall vertically overhead at the Equator (0°), and the Circle of Illumination passes through both poles,
causing equal duration of day and night (12 hours each) everywhere on Earth.
Geography • Chapter 3: Rotation and Revolution Page 1 of 5
, 9. Name one country where the Sun will be overhead on 22 December.
• Australia (or South Africa / Argentina / Brazil).
10. On which latitude will the Sun be overhead on 21 June?
• 23½°N (Tropic of Cancer).
11. Name two countries where the Sun will be overhead on 21 June.
• India and Mexico.
12. What will be the altitude of the Sun on 21 June at:
Formula: Altitude = (90° − Latitude) + Declination of Sun (23½°N)
• (a) Equator (0°): 66½°
• (b) 66½°N (Arctic Circle): 47°
• (c) 66½°S (Antarctic Circle): 0°
• (d) 23½°N (Tropic of Cancer): 90°
13. What will be the altitude of the Sun on 22 December at the:
Formula: Altitude = (90° − Latitude) − Declination of Sun (23½°S)
• (a) Equator: 66½°
• (b) Arctic Circle (66½°N): 0°
• (c) Antarctic Circle (66½°S): 47°
• (d) Tropic of Cancer (23½°N): 43°
14. What is the altitude of the Sun at the Arctic Circle on:
• (a) 21 March: 23½°
• (b) 21 June: 47°
• (c) 22 December: 0°
15. Which is the longest day of the Southern Hemisphere?
• 22 December (Winter Solstice for Northern Hemisphere).
16. On what date does the Arctic Circle experience the 'Midnight Sun'?
• 21 June.
17. What is the duration of daytime at the Tropic of Cancer on:
• (a) Equinoxes: 12 hours
• (b) Summer Solstice: 13 hours 27 minutes
• (c) Winter Solstice: 10 hours 33 minutes
18. What causes twilight and dawn?
• Scattering and reflection of Sun's rays by air molecules, dust particles, and moisture in the
atmosphere while the Sun is below the horizon.
19. Why is the duration of twilight longer in high latitudes than at the equator?
• In high latitudes, the path of the Sun is inclined at a low/slanting angle, taking longer to sink 18°
below the horizon. At the equator, the Sun rises and sets almost vertically, crossing the 18° threshold
rapidly.
Geography • Chapter 3: Rotation and Revolution Page 2 of 5
Chapter 3: Rotation and Revolution
II. Answer the following questions briefly
1. What is the name given to the path along which the Earth travels when moving round the Sun?
How long does this movement take?
• Path: Elliptical orbit.
• Duration: 365¼ days (365 days and 6 hours).
2. Name an effect of the Earth's rotation.
• Alternation of day and night.
3. State two effects of West-to-East rotation of the Earth.
• The Sun, Moon, and stars appear to rise in the east and set in the west.
• Difference in local time between different places on Earth (4 minutes for every degree of longitude).
4. What causes light flattening of the Earth at the two poles?
• The centrifugal force generated by the speed of Earth's rotation.
5. What is a leap year?
• A year having 366 days (with February having 29 days) occurring once every four years to adjust for
the accumulated extra ¼ day (6 hours × 4 = 24 hours) of Earth's revolution.
6. What is meant by the inclination of the Earth's axis? What are its two main effects?
• Meaning: The tilt of the Earth's axis at an angle of 23½° from the vertical (66½° to the orbital plane).
• Two main effects:
1. Variation in the length of day and night throughout the year.
2. Occurrence and changing of seasons.
7. Define briefly the following terms and mention the dates on which these are experienced:
• (a) Solstice: The position when the Sun is directly overhead at one of the tropics.
Dates: Summer Solstice (21 June), Winter Solstice (22 December).
• (b) Equinox: The position when the Sun is vertically overhead at the Equator, resulting in equal day
and night.
Dates: Vernal Equinox (21 March), Autumnal Equinox (23 September).
• (c) Aphelion: The position where Earth is farthest from the Sun (≈ 152 million km).
Date: 4 July.
• (d) Perihelion: The position where Earth is closest to the Sun (≈ 147 million km).
Date: 3 January.
8. Explain fully the meaning of the term 'Equinox'.
• Derived from Latin meaning equal night. On these days (21 March and 23 September), the Sun's rays
fall vertically overhead at the Equator (0°), and the Circle of Illumination passes through both poles,
causing equal duration of day and night (12 hours each) everywhere on Earth.
Geography • Chapter 3: Rotation and Revolution Page 1 of 5
, 9. Name one country where the Sun will be overhead on 22 December.
• Australia (or South Africa / Argentina / Brazil).
10. On which latitude will the Sun be overhead on 21 June?
• 23½°N (Tropic of Cancer).
11. Name two countries where the Sun will be overhead on 21 June.
• India and Mexico.
12. What will be the altitude of the Sun on 21 June at:
Formula: Altitude = (90° − Latitude) + Declination of Sun (23½°N)
• (a) Equator (0°): 66½°
• (b) 66½°N (Arctic Circle): 47°
• (c) 66½°S (Antarctic Circle): 0°
• (d) 23½°N (Tropic of Cancer): 90°
13. What will be the altitude of the Sun on 22 December at the:
Formula: Altitude = (90° − Latitude) − Declination of Sun (23½°S)
• (a) Equator: 66½°
• (b) Arctic Circle (66½°N): 0°
• (c) Antarctic Circle (66½°S): 47°
• (d) Tropic of Cancer (23½°N): 43°
14. What is the altitude of the Sun at the Arctic Circle on:
• (a) 21 March: 23½°
• (b) 21 June: 47°
• (c) 22 December: 0°
15. Which is the longest day of the Southern Hemisphere?
• 22 December (Winter Solstice for Northern Hemisphere).
16. On what date does the Arctic Circle experience the 'Midnight Sun'?
• 21 June.
17. What is the duration of daytime at the Tropic of Cancer on:
• (a) Equinoxes: 12 hours
• (b) Summer Solstice: 13 hours 27 minutes
• (c) Winter Solstice: 10 hours 33 minutes
18. What causes twilight and dawn?
• Scattering and reflection of Sun's rays by air molecules, dust particles, and moisture in the
atmosphere while the Sun is below the horizon.
19. Why is the duration of twilight longer in high latitudes than at the equator?
• In high latitudes, the path of the Sun is inclined at a low/slanting angle, taking longer to sink 18°
below the horizon. At the equator, the Sun rises and sets almost vertically, crossing the 18° threshold
rapidly.
Geography • Chapter 3: Rotation and Revolution Page 2 of 5
