Keeping Time with the Skies Class 8 - Chapter 11 Curiosity

Q 1
Question
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.
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Q 2
Question
Amol was born on 6th of May on a full Moon day. Does his birthday fall on the full Moon day every year? Explain your answer.
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Q 3
Question
Name two things that are incorrect in Fig. 11.10 (a crescent Moon shown among clouds with stars).
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Q 4
Question
Look at the pictures of the Moon in Fig. 11.11 (A–F). (i) Match each phase below to the correct picture label. (ii) List the picture labels of phases that are never seen from Earth.
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Q 5
Question
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?
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Q 6
Question
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?
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Q 7
Question
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?
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Q 8
Question
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.
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Q 9
Question
On a particular night, Vaishali saw the Moon in the sky from sunset to sunrise. What phase of the Moon would she have noticed?
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Q 10
Question
If we stopped having leap years, in approximately how many years would the Indian Independence day happen in winter?
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Q 11
Question
What is the purpose of launching artificial satellites?
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Q 12
Question
On which periodic phenomenon are the following measures of time based: (i) day (ii) month (iii) year?
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Project 1
Project
The Moon's crescent always faces towards the Sun. On days when you see the crescent Moon, point your finger towards the Sun, and slowly move it across the sky towards the Moon taking as short a path as you can. Note how your finger always crosses the illuminated part of the Moon first.
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Key Points
The crescent's lit side always points to the Sun.
Key Points / Good Practices
Do this safely without looking straight at the Sun.
Trace the shortest path from the Sun to the Moon.
Your finger crosses the bright side of the Moon first.
This shows the Moon shines by reflecting sunlight.
The line joining the crescent tips marks the Moon's diameter.
Record your observation with a simple sketch.
The crescent's bright side always faces the Sun, proving the Moon reflects sunlight.

Project 2
Project
Most of the dates in the Indian National Calendar always map to the same dates in the Gregorian calendar. Can you find out which ones may differ for certain years?
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Key Points
Leap years shift the start of Chaitra.
Key Points / Good Practices
Most Indian National Calendar dates match fixed Gregorian dates.
The year normally starts on 22 March.
In a leap year, a day is added to Chaitra, the first month.
Then the new year begins on 21 March instead.
So dates around Chaitra can differ in leap years.
Check a few leap years to confirm the shift.
The mapping shifts mainly in leap years, when Chaitra gains a day and the year starts on 21 March.

Project 3
Project
Different states in India celebrate the New Year according to their local cultures. Find out the names of the New Year festival celebrated in any 10 states of India. Also find out whether it is based on the lunar, solar, or luni-solar calendar.
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Key Points
Indian New Year festivals follow different calendars.
Key Points / Good Practices
List New Year festivals from 10 states, such as Ugadi and Baisakhi.
Include Pohela Boishakh, Puthandu, and Vishu.
Solar ones like Baisakhi and Puthandu fall on nearly fixed dates.
Luni-solar ones like Ugadi and Gudi Padwa shift slightly.
Note which calendar each follows in a neat table.
Use reliable sources and cite them.
Indian New Year festivals span solar and luni-solar calendars, which sets whether their dates stay fixed or shift.

Project 4
Project
Collect Gregorian calendars for the last five years. For each year, list the dates of Eid-ul-Fitr and Diwali in a table. Notice that Eid-ul-Fitr moves earlier by about 11 days each year. Check whether Diwali follows a steady pattern or has sudden jumps, and guess which year may have included an intercalary month (Adhikamaasa).
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Key Points
Eid drifts steadily; Diwali jumps when a month is added.
Key Points / Good Practices
Tabulate Eid-ul-Fitr and Diwali dates for five years.
Eid follows a purely lunar calendar, so it moves about 11 days earlier yearly.
Diwali follows a luni-solar calendar, so it stays near the same season.
A sudden jump in Diwali's date signals an added month.
That added month is the intercalary month (Adhikamaasa).
Confirm using a luni-solar calendar for that year.
Eid drifts steadily earlier while Diwali jumps in the year an Adhikamaasa is inserted.

Project 5
Project
Every morning on your way to school, notice the direction in which the Sun rises. Sketch the eastern horizon with markers like trees or buildings. At the start of each month for a year, mark the Sun's position and label it. At the end of the year, see if the sunrise positions shift, and link this to Uttarayan and Dakshinayan.
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Key Points
The sunrise point shifts north and south over the year.
Key Points / Good Practices
Pick one fixed spot and the same time each month.
Use trees or buildings as steady markers on your sketch.
Mark and label the sunrise point each month.
The Sun rises north of east toward June (Uttarayan).
It rises south of east toward December (Dakshinayan).
Link your shifting marks to these ancient observations.
The sunrise point moves north and south through the year, matching the Uttarayan and Dakshinayan our ancestors noticed.
💡 A step further
Tides are the rise and fall of sea-water levels.
Tides follow a regular pattern.
A similar tide comes about 50 minutes later each day.
The Moon also rises about 50 minutes later each day.
Tide levels are closely related to the Moon's position and phase.