Question 1

Have you ever seen the Moon during the day? Why do you think it is sometimes possible when the Sun is up? (Page 170)

Accepted Answer

Yes, the Moon can often be seen during the day, especially in its waxing and waning phases. This happens because the Moon reflects sunlight, and during certain phases, it is high enough in the sky while the Sun is also up, making it visible.

Question 2

Imagine you lived on the Moon instead of Earth. What would you mean by a day, a month, or a year? (Page 170)

Accepted Answer

A day on the Moon (from one sunrise to the next) would be about 29.5 Earth days.
A month might be defined by one complete orbit around Earth (which is also about 27.3 Earth days).
A year is the time the Earth to complete one orbit around the Sun, which you could still observe from the Moon in about 365 Earth days.

Question 3

What would happen if Earth had two moons instead of one? How would that change the night sky? (Page 170)

Accepted Answer

If Earth had two moons:
The night sky would be brighter and more dynamic.
There could be more frequent eclipses.
The gravitational pull on Earth would be different, possibly affecting tides and even weather patterns.
The two moons might cross paths, creating fascinating views or even risks of collision over long periods.

Question 4

If we didn’t have clocks or calendars, how else could we measure time? (Page 170)

Accepted Answer

We could measure time by:
Observing the position of the Sun (sunrise, noon, sunset).
Using the phases of the Moon to count months.
Tracking stars and constellations that change with the seasons.
Using natural events, like plant flowering or animal behaviour, to mark the passage of time.
NCERT Class 8 Science Chapter 11 Question Answer Keeping Time with the Skies (Exercise)
Keep the Curiosity Alive (Pages 187-189)

Question 5

Malini saw the Moon overhead in the sky at sunset.
(i) Draw the phase of the Moon that Malini saw.
(ii) Is the Moon in the waxing or the waning phase?

Accepted Answer

(i) At sunset, the Moon is overhead only during the first quarter (a week after New Moon), when the right half is illuminated. So, we need to draw a half Moon (right half bright, left half dark).
(ii) Waxing phase (because it occurs after New Moon and the bright part is increasing).

Question 6

Ravi said, “I saw a crescent Moon, and it was rising in the East when the Sun was setting.” Kaushalya said, “Once I saw the gibbous Moon during the afternoon in the East.” Who out of the two is telling the truth?

Accepted Answer

Kaushalya is telling the truth because gibbous Moons can be seen in the East during the afternoon. Ravi’s statement is incorrect because Crescent Moons do not rise in the East at sunset. A crescent Moon appears just after the New Moon (waxing crescent) or just before the New Moon (waning crescent). Waxing crescent is visible after sunset in the western sky, not rising in the east, and waning crescent rises just before sunrise, not at sunset.

Question 7

Scientific studies show that the Moon is getting farther away from the Earth and slower in its revolution. Will luni-solar calendars need an intercalary month more often or less often?

Accepted Answer

Luni-solar calendars will need an intercalary month more often as the Moon moves farther and slower, and it takes longer to complete a cycle. So, a lunar year becomes even shorter compared to the solar year.

Question 8

A total of 37 full Moons happen during 3 years in a solar calendar. Show that at least two of the 37 full moons must happen during the same month of the solar calendar.

Accepted Answer

Yes, at least two full Moons must happen in the same solar month.
A solar calendar has 12 months × 3 years = 36 months.
37 full Moons in 36 months, at least one month must have 2 full Moons.

Source: This question is from Keeping Time with the Skies, Science &mdash; Class 8, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Keeping Time with the Skies: Total, Full, Moons, Happen, Years, Solar. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 8 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Keeping Time with the SkiesQ1: Have you ever seen the Moon during the day? Why do you think it is sometimes possible when the Sun...
Q10: If we stopped having leap years, in approximately how many years would the Indian Independence Day...
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Q2: Imagine you lived on the Moon instead of Earth. What would you mean by a day, a month, or a year?...
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Practice more questions from Keeping Time with the Skies &mdash; Science, Class 8 CBSE

Question 9

On a particular night, Vaishali saw the Moon in the sky from sunset to sunrise. What phase of the Moon would she have noticed?

Accepted Answer

As the Moon is visible all night long only on a Full Moon, it is a Full Moon.

Source: This question is from Keeping Time with the Skies, Science &mdash; Class 8, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Keeping Time with the Skies: Particular, Night, Vaishali, Saw, Moon, Sky. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 8 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Keeping Time with the SkiesQ1: Have you ever seen the Moon during the day? Why do you think it is sometimes possible when the Sun...
Q10: If we stopped having leap years, in approximately how many years would the Indian Independence Day...
Q12: On which periodic phenomenon are the following measures of time based: (i) day (ii) month (iii)...
Q2: Imagine you lived on the Moon instead of Earth. What would you mean by a day, a month, or a year?...
Q3: What would happen if Earth had two moons instead of one? How would that change the night sky? (Page...
Practice more questions from Keeping Time with the Skies &mdash; Science, Class 8 CBSE

Question 10

If we stopped having leap years, in approximately how many years would the Indian Independence Day happen in winter?

Accepted Answer

One leap year adds ~1 day every 4 years.
Without leap years, the calendar shifts by 1 day every 4 years.
There are roughly 183 days between 15 August (monsoon) and winter (mid-February).
183 days × 4 = 732 years
In approximately 730-732 years, 15 August would occur in winter.

Question 11

What is the purpose of launching artificial satellites?

Accepted Answer

Artificial satellites are launched for:
Communication
Navigation
Weather monitoring
Scientific research
Disaster management
Earth observation

Source: This question is from Keeping Time with the Skies, Science &mdash; Class 8, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Keeping Time with the Skies: Purpose, Launching, Artificial, Satellites, Keeping Time with the Skies, Science. These are fundamental topics in Science that students are expected to master as part of the CBSE Class 8 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberRead the question carefully and identify all parts before answering.
Use the terminology specific to this subject and chapter.
Review the textbook content for this chapter before attempting questions.
Practice writing concise, well-structured answers within time limits.
Related Questions from Keeping Time with the SkiesQ1: Have you ever seen the Moon during the day? Why do you think it is sometimes possible when the Sun...
Q10: If we stopped having leap years, in approximately how many years would the Indian Independence Day...
Q12: On which periodic phenomenon are the following measures of time based: (i) day (ii) month (iii)...
Q2: Imagine you lived on the Moon instead of Earth. What would you mean by a day, a month, or a year?...
Q3: What would happen if Earth had two moons instead of one? How would that change the night sky? (Page...
Practice more questions from Keeping Time with the Skies &mdash; Science, Class 8 CBSE

Question 12

On which periodic phenomenon are the following measures of time based:
(i) day
(ii) month
(iii) year?

Accepted Answer

(i) Day → Earth’s rotation
(ii) Month → Moon’s revolution (phases of the Moon)
(iii) Year → Earth’s revolution around the Sun.
Class 8 Keeping Time with the Skies Question Answer (Activities)
Activity 11.1: Let us Explore (Pages 171-172)
Documenting Changes in the Moon’s Appearance
Analysis Questions: