the-moon-and-its-phases MCQs for UPSC Prelims

25 practice questions on the-moon-and-its-phases from the Earth, Moon, and the Sun section of the UPSC Prelims syllabus. 25 come with a written explanation. Try the sample set below - the answer stays hidden until you ask for it.

7 Easy 13 Medium 5 Hard

Sample questions

Q1
easy

The Moon is described as a non-luminous body because it

  1. A is far away from us
  2. B looks white in colour
  3. C has no light of its own
  4. D is smaller than the Earth
Show answer and explanation

Correct answer: C - has no light of its own

Non-luminous means an object does not produce light, and the Moon only sends back the sunlight falling on it. Size, distance and colour have nothing to do with the word. A firefly is tiny and still luminous, while a huge dark rock is not.

Q2
hard

On a new moon day the Moon is high in the sky along with the Sun, yet we cannot see it. The reason is that

  1. A the half of the Moon lit by the Sun is turned away from the Earth
  2. B the Moon has moved behind the Sun for that day
  3. C the Moon stops reflecting light for one day each month
  4. D the Earth's shadow falls on the Moon at every new moon
Show answer and explanation

Correct answer: A - the half of the Moon lit by the Sun is turned away from the Earth

The Moon is right there in the daytime sky, but the sunlit half faces away from us and the dark half faces the Earth, so there is nothing bright to see. The Moon travels around the Earth and does not go behind the Sun. The Earth's shadow points away from the Sun, so it cannot reach the Moon at new moon, and the Moon reflects light all the time.

Q3
easy

The night on which the whole of the Moon's disc is seen bright is called

  1. A a new moon night
  2. B a half moon night
  3. C a full moon night
  4. D an eclipse night
Show answer and explanation

Correct answer: C - a full moon night

When the entire disc appears lit, the night is called a full moon night. On a new moon night no bright part is seen at all. A half moon night shows only one half of the disc lit, and an eclipse is a shadow event that happens only occasionally.

Q4
easy

The different shapes of the bright part of the Moon seen on different nights are called its

  1. A seasons
  2. B phases
  3. C eclipses
  4. D orbits
Show answer and explanation

Correct answer: B - phases

The changing shapes are known as the phases of the Moon, and they repeat in a regular cycle. An eclipse is a rare shadow event and not a monthly change of shape. An orbit is a path, and seasons belong to the Earth's yearly journey around the Sun.

Q5
medium

We always see the same face of the Moon because the Moon

  1. A does not spin at all
  2. B takes the same time to spin once as it takes to travel once around the Earth
  3. C is joined to the Earth by an invisible rod
  4. D spins much faster than it travels around the Earth
Show answer and explanation

Correct answer: B - takes the same time to spin once as it takes to travel once around the Earth

Its spin and its trip around the Earth are matched in time, so it turns by just the right amount to keep one face pointed at us. A Moon that never spun would show us every side in turn as it went round. A much faster spin would also let us see all sides, and nothing physically joins the two bodies.

Q6
medium

The Moon appears to change its shape from night to night because

  1. A as it travels around the Earth we see different amounts of its sunlit half
  2. B clouds hide a different part of it each night
  3. C the Earth's shadow covers a part of it every night
  4. D the Moon really changes its shape each night
Show answer and explanation

Correct answer: A - as it travels around the Earth we see different amounts of its sunlit half

Half of the Moon is always lit by the Sun, but as the Moon moves around the Earth we look at that lit half from changing directions, so we see more or less of it. The Earth's shadow reaches the Moon only rarely, during a lunar eclipse. Clouds hide the Moon only sometimes, and the Moon is a solid rocky body whose shape does not change.

Q7
medium

The side of the Moon that can never be seen from the Earth is often called its far side. This side

  1. A faces the Sun at all times
  2. B never receives any sunlight at all
  3. C receives sunlight at times, just as the side we see does
  4. D is completely flat, unlike the side we see
Show answer and explanation

Correct answer: C - receives sunlight at times, just as the side we see does

Sunlight falls on every part of the Moon in turn as it spins, so the far side has its own periods of day and night. It is hidden from the Earth, not from the Sun. It does not permanently face the Sun either, and photographs from spacecraft show it is rough and covered with craters.

Q8
medium

Assertion (A): We can see the Moon in the night sky. Reason (R): The Moon is much closer to the Earth than the Sun is.

  1. A Both A and R are true, and R is the correct explanation of A
  2. B Both A and R are true, but R is not the correct explanation of A
  3. C A is true, but R is false
  4. D A is false, but R is true
Show answer and explanation

Correct answer: B - Both A and R are true, but R is not the correct explanation of A

Both statements are true, but nearness is not what makes the Moon visible. We see it because sunlight falls on it and is reflected to our eyes. A nearby body with no light falling on it would stay invisible, which shows that R does not explain A.

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