Keeping Time with the Skies — Class 8 MCQs with Answers

Keeping Time with the Skies — important questions & MCQs with answers (Class 8 Science)

6 solved questions from this chapter's difficulty levels, each with its answer and explanation. Tap an option to check yourself.

0 of 6 answered

1. Q1 of 6Easy

   The Moon shines because it:

   Areflects sunlightBproduces its own lightCis on fireDis a star
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   Answer: reflects sunlight

   Explanation: The Moon has no light source of its own; it is visible because its surface reflects sunlight, unlike self-luminous stars such as the Sun.

2. Q2 of 6Easy

   A calendar based on the phases of the Moon is a:

   Asolar calendarBlunar calendarCsundialDclock
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   Answer: lunar calendar

   Explanation: A lunar calendar tracks months using the Moon's cycle of phases, unlike a solar calendar, which follows Earth's orbit around the Sun.

3. Q3 of 6Medium

   As the Earth rotates, the side facing the Sun has ___ and the other side has ___.

   Anight; dayBsummer; winterCnoon; noonDday; night
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   Answer: day; night

   Explanation: As Earth rotates, the hemisphere facing the Sun experiences day while the opposite, shadowed hemisphere experiences night.

4. Q4 of 6Medium

   During a solar eclipse, the ___ comes between the Sun and the Earth.

   Aa starBa cloudCthe Earth's shadowDMoon
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   Answer: Moon

   Explanation: A solar eclipse happens when the Moon moves directly between the Sun and Earth, blocking sunlight from reaching part of Earth's surface.

5. Q5 of 6Hard

   If tonight is a full Moon, in about two weeks it will be:

   Aanother full MoonBnew MoonCa solar eclipseDdaytime
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   Answer: new Moon

   Explanation: Half of the roughly 29.5-day lunar cycle is about 15 days, so two weeks after a full Moon brings the opposite phase — new Moon.

6. Q6 of 6Hard

   Which correctly pairs a calendar with its basis?

   Alunar calendar → Moon's phases; solar calendar → Earth's orbitBlunar → Sun; solar → MoonCboth based on starsDboth based on tides
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   Answer: lunar calendar → Moon's phases; solar calendar → Earth's orbit

   Explanation: Lunar calendars are built on the Moon's cycle of phases, while solar calendars are built on Earth's orbit around the Sun.

Keeping Time with the Skies notes: key concepts (Class 8 Science)

This chapter shows how people learned to keep time by watching the sky. The Moon shines by reflecting sunlight, and as it orbits the Earth we see its phases — from the invisible new Moon, through the growing waxing period (Shukla Paksha), to the full Moon, and back through the waning period (Krishna Paksha) — a cycle of about 29.5 days, a lunar month. From these cycles came lunar calendars, while the Earth's roughly 365-day revolution around the Sun gave the solar (Gregorian) calendar with its leap years. The Earth's rotation makes day and night, its revolution makes the year and seasons, and the alignment of the Sun, Earth and Moon causes eclipses.

The Moon reflects sunlight

The Moon makes no light of its own; we see the half of it that is lit by the Sun.

Phases of the Moon

The changing shapes of the bright Moon: the invisible new Moon, the full bright disc of the full Moon, and the shapes in between.

Waxing and waning

In the waxing period (Shukla Paksha) the lit part grows towards full Moon; in the waning period (Krishna Paksha) it shrinks towards new Moon.

Cause of the phases

The phase we see depends on the relative positions of the Sun, Moon and Earth as the Moon orbits, so different amounts of its lit half face us.

Lunar month

The cycle from one full Moon to the next takes about 29.5 days, which is one lunar month; twelve of them make a lunar year of about 354 days.

Lunar calendar

A calendar based on the Moon's phases; because a lunar year is about 11 days shorter than a solar year, its dates drift across the seasons.

Solar calendar

A calendar based on the Earth's revolution around the Sun; the Gregorian calendar is solar, with months adjusted to total 365 days so the seasons stay fixed.

Leap year

The Earth takes about an extra quarter day beyond 365 days each year, so a leap day (February 29) is added every four years to keep the calendar in step.

Day and night

The Earth's rotation on its axis, taking about 24 hours, turns each side towards and away from the Sun, giving day and night.

Year and seasons

One revolution of the Earth around the Sun, about 365 days, is a year; the Earth's tilt together with this revolution gives the changing seasons.

Eclipses

A lunar eclipse happens when the Earth's shadow falls on the Moon (only at full Moon); a solar eclipse happens when the Moon comes between the Sun and Earth (only at new Moon). Both are rare.