NCERT Solutions for Class 8 Science Chapter 11 - Keeping Time with the Skies

NCERT Solutions For Class 8 Science Chapter 11 - PDF Download

Given below is the link to the PDF for the chapter Keeping Time with the Skies. Students can use this resource to complete their homework and do the revision quickly. The NCERT Solutions for Class 8 help build a strong foundation for higher classes and competitive exams.

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Access to Class 8 Science Chapter 11 Solutions (Exercise Questions)

Provided below are the detailed answers to all the questions provided in the textbook. These solutions are carefully prepared to avoid any difficulty for students. Doing the regular practice of Keeping Time with the Skies questions and answers helps students understand the concepts easily. Solutions also explain the role of artificial satellites in communication, weather prediction, etc.

Question 1: State whether the following statements are True or False.

(i) We can only see that part of the Moon which reflects sunlight towards us.

(ii) The shadow of Earth blocks sunlight from reaching the Moon, causing phases.

(iii) Calendars are based on various astronomical cycles which repeat in a predictable manner.

(iv) The Moon can only be seen at night.

Answer:

(i) We can only see that part of the Moon which reflects sunlight towards us. - True

(ii) The shadow of Earth blocks sunlight from reaching the Moon, causing phases. - False

(iii) Calendars are based on various astronomical cycles which repeat in a predictable manner. - True

(iv) The Moon can only be seen at night.- False

Question 2: Amol was born on the 6th of May on a full Moon day. Does his birthday fall on the full Moon day every year? Explain your answer.

Answer: No, Amol’s birthday will not fall on the full moon day every year. This is because the Moon follows a different cycle, which is known as the lunar cycle. And this lunar cycle does not match our calendar months. So, the date of the full moon changes every year.

Question 3: Name two things that are incorrect in the figure given below.

Answer: The two things that are incorrect in the figure are:

• Stars are shown near the moon, which is wrong. Stars are only visible at night.

• The shadow present on the moon is shown in the wrong direction.

Question 4: Look at the pictures of the Moon in the figure given below, and answer the following questions.

(i) Write the correct panel number corresponding to the phases of the Moon shown in the pictures above.

(ii) List the picture labels of the phases of the Moon that are never seen from Earth.

Answer:

(i)

(ii) B is the picture label of the moon phase, which is never seen from the Earth as the moon is not illuminated during that phase.

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?

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.

(ii) The moon is in the 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?

Answer: Ravi said he saw a crescent moon rising in the east at sunset, but this is not possible because a crescent moon wouldn't be rising in the east when the sun was setting. On the other hand, Kaushalya said she saw a gibbous moon during the afternoon in the east. This is possible because a waxing gibbous Moon rises in the afternoon and is often visible before sunset.

So, Kaushalya is telling the truth, and Ravi is not.

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?

Answer: Scientific studies show that the moon is getting farther away from the Earth and slower in its revolution. Because of this, each lunar month will become a little longer.

Luni-solar calendars are different kinds of calendars that use the moon’s phases for counting days and months. The 12 lunar months add up to 354 days and thus fall short by around 11 days compared to the solar year. Thus, every 2–3 years, the difference becomes close to a full month. But since the lunar month becomes longer, the difference between the lunar year and the solar year becomes smaller. So, an intercalary month is needed less often..

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.

Answer: In three years, if we calculate the total months would be 36. But as it is mentioned in the question, the total number of full moons in 3 years is 37, then it means one month will have 2 full moons. This occurs because the number of full moons is more than the number of months.

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?

Answer: If Vaishali saw the moon in the sky from sunset to sunrise, then it is the full moon phase. It is because the full moon rises at sunset, then remains visible all night, and sets as sunrise.

Question 10: If we stopped having leap years, in approximately how many years would the Indian Independence Day happen in winter?

Answer: If we stop having leap years, the calendar will slowly shift. After around 500-600 years, 15th August, which is Independence Day, will fall in winter. This happens because the calendar will not match the Earth’s revolution around the sun.

Question 11: What is the purpose of launching artificial satellites?

Answer: The main purpose of launching artificial satellites is they help us in many ways, like communication, navigation, weather monitoring, disaster management, and scientific research as well.

Question 12: On which periodic phenomenon are the following measures of time based: (i) day, (ii) month, (iii) year?

Answer:

(i) Day - Based on the rotation of the Earth on its axis

(ii) Month - Based on the revolution of the Moon around the Earth

(iii) Year - Based on the revolution of the Earth around the Sun

Also, check the NCERT Books and the NCERT Syllabus here

• NCERT Books Class 8 Science

• NCERT Syllabus Class 8 Science

• NCERT Books Class 8

• NCERT Syllabus Class 8

Approach to Solve Questions of Class 8 Science Chapter 11 Solutions

Students can follow the steps given below to answer the questions effectively. Keeping Time with Skies questions and answers provides information about the sun, the moon, and the Earth. These answers allow students to improve their thinking skills and help them relate science to everyday life.

• Students can start by understanding how the sun, the moon, and the Earth help us measure time.

• They can learn about different phases of the Moon and how its form changes regularly. Students can take help from the NCERT Solutions for Class 8 Science Chapter 11 Keeping Time with Skies.

• Students are advised to prepare flow charts and learn the phases with the diagrams. This makes it easy to remember the phases during exams.

• Learn about different types of calendars, such as solar, lunar, luni-solar, Indian national calendar, etc. They are all included in the Science NCERT Class 8 PDF Solutions.

• Solve and practice different forms of questions from the NCERT Solutions for Class 8 Science to get familiar with the question pattern.

NCERT Solutions For Class 8th: Subject-wise

• NCERT Solutions for Class 8 Maths

Important Topics of Chapter 11 NCERT Class 8 Science

This chapter helps students understand how natural movements in the sky, like phases of the moon, etc., help us to measure time. It also includes concepts of day, months, and years based on the sun, moon, and the Earth. Students can use Keeping Time with Skies Class 8 Solutions for detailed explanations. Given below are a few important topics of this chapter.

• How does the Moon’s appearance change, and why

• Phases of the Moon

• How calendars came into existence

• Different types of calendars

• Are festivals related to astronomical phenomena?

• Solar and Lunar eclipses

• Measurement of time using celestial bodies

• Artificial satellites

Important Question from Class 8 Science Chapter 11 Solutions

Practicing different types of questions helps students gain a better understanding of the chapter. It allows them to connect the concepts of sun, moon, and earth with real-life observations. Given below is a question from this chapter that makes students understand the difficulty level. To gain clarity, students can refer to Keeping Time with the Skies Class 8 Solutions.

Question 1: Which phenomenon occurs when the Moon comes directly between the Earth and the Sun, blocking sunlight from reaching the Earth?

Options

a) Lunar eclipse

b) Solar eclipse

c) New moon

d) Full moon

Answer: The correct answer is option (b), Solar Eclipse

Explanation: A solar eclipse happens when the Moon comes directly between the Earth and the Sun. It blocks some or all sunlight from reaching the Earth's surface, which forms a shadow. This can only occur during the new moon phase.

NCERT Solutions for Class 8 Science: Chapter-wise

Given below are the links that provide access to well-structured answers for every chapter in the syllabus. These solutions are prepared by subject experts and follow the latest NCERT guidelines. It helps students strengthen concepts, improve problem-solving skills, and prepare effectively for exams.