Class 7 Science Chapter 12 NCERT Book - Earth, Moon, and the Sun

 Page 1


Earth, Moon, and 
the Sun
12
Earth, Moon, and 
the Sun
12
One morning in Kanniyakumari, Tamil Nadu, 12-year-old 
Rashmika was eagerly cycling to school. She was excited. That was 
the day her science teacher had dedicated a class for students to 
share and try to explain interesting observations.
Rashmika had been noticing that the coconut tree shadows 
were long in the morning but shorter in the afternoon on her 
way back. She thought about it and decided that the size of the 
shadows changed because the Sun moved across the sky during 
the day. But she also remembered learning that the Earth moved 
around the Sun (in chapter ‘Beyond Earth’ in the Grade 6 Science 
textbook Curiosity) so she was puzzled. She wondered — does the 
Sun move in the sky? Or does the Earth move?
Chapter 12.indd   169 4/3/2025   4:57:11 PM
Page 2


Earth, Moon, and 
the Sun
12
Earth, Moon, and 
the Sun
12
One morning in Kanniyakumari, Tamil Nadu, 12-year-old 
Rashmika was eagerly cycling to school. She was excited. That was 
the day her science teacher had dedicated a class for students to 
share and try to explain interesting observations.
Rashmika had been noticing that the coconut tree shadows 
were long in the morning but shorter in the afternoon on her 
way back. She thought about it and decided that the size of the 
shadows changed because the Sun moved across the sky during 
the day. But she also remembered learning that the Earth moved 
around the Sun (in chapter ‘Beyond Earth’ in the Grade 6 Science 
textbook Curiosity) so she was puzzled. She wondered — does the 
Sun move in the sky? Or does the Earth move?
Chapter 12.indd   169 4/3/2025   4:57:11 PM
Curiosity  Textbook of Science  Grade 7
170
12.1 Rotation of the Earth
You might have also noticed that the Sun rises in the East and sets in 
the West. Have you ever wondered why? Let us try to understand 
why. Have you ever enjoyed riding a merry-go-round at a park or 
at your school? Let us go back to riding a merry-go-round!
Activity 12.1: Let us explore
? Sit on a merry-go-round facing towards the outer side as 
shown in Fig. 12.1.
Fig. 12.1: A girl observing objects around 
her while riding a merry-go-round
? Ask someone to turn the merry-go-
round slowly in the anti-clockwise 
direction as shown in Fig. 12.1. While 
you are sitting on the moving merry-
go-round, look around you. Do the 
objects around you appear to be 
moving? In which direction do they 
appear to be moving? 
While you turn in the anti-clockwise 
direction, the objects appear to turn 
around you in the opposite direction, that 
is, in the clockwise direction.
? Now ? x your gaze at a particular tree 
(or a building) ahead of you while 
sitting on the merry- go-round turning 
around in anti-clockwise direction.
In which direction do you ? nd the tree turning around you? Is 
it in your view all the time?
The tree appears to turn around you in the opposite direction, 
that is, the clockwise direction. The tree appears in your view 
from your left-hand side and then moves out of your view on the 
right-hand side when you view it from a merry-go-round turning 
around in anti-clockwise direction.
Using the observations made by us while riding a merry-go-
round, let us now think. When we view from the Earth, the Sun 
appears in the East, moves across the sky from the East to the West 
and disappears in the West. Does it indicate that the Sun is moving 
in the sky? Or might it be that the Earth itself is turning around 
and the Sun just appears to move?
The fact is that the Sun appears to be moving because we view 
it from the Earth, which is turning around itself. 
Chapter 12.indd   170 4/3/2025   4:57:12 PM
Page 3


Earth, Moon, and 
the Sun
12
Earth, Moon, and 
the Sun
12
One morning in Kanniyakumari, Tamil Nadu, 12-year-old 
Rashmika was eagerly cycling to school. She was excited. That was 
the day her science teacher had dedicated a class for students to 
share and try to explain interesting observations.
Rashmika had been noticing that the coconut tree shadows 
were long in the morning but shorter in the afternoon on her 
way back. She thought about it and decided that the size of the 
shadows changed because the Sun moved across the sky during 
the day. But she also remembered learning that the Earth moved 
around the Sun (in chapter ‘Beyond Earth’ in the Grade 6 Science 
textbook Curiosity) so she was puzzled. She wondered — does the 
Sun move in the sky? Or does the Earth move?
Chapter 12.indd   169 4/3/2025   4:57:11 PM
Curiosity  Textbook of Science  Grade 7
170
12.1 Rotation of the Earth
You might have also noticed that the Sun rises in the East and sets in 
the West. Have you ever wondered why? Let us try to understand 
why. Have you ever enjoyed riding a merry-go-round at a park or 
at your school? Let us go back to riding a merry-go-round!
Activity 12.1: Let us explore
? Sit on a merry-go-round facing towards the outer side as 
shown in Fig. 12.1.
Fig. 12.1: A girl observing objects around 
her while riding a merry-go-round
? Ask someone to turn the merry-go-
round slowly in the anti-clockwise 
direction as shown in Fig. 12.1. While 
you are sitting on the moving merry-
go-round, look around you. Do the 
objects around you appear to be 
moving? In which direction do they 
appear to be moving? 
While you turn in the anti-clockwise 
direction, the objects appear to turn 
around you in the opposite direction, that 
is, in the clockwise direction.
? Now ? x your gaze at a particular tree 
(or a building) ahead of you while 
sitting on the merry- go-round turning 
around in anti-clockwise direction.
In which direction do you ? nd the tree turning around you? Is 
it in your view all the time?
The tree appears to turn around you in the opposite direction, 
that is, the clockwise direction. The tree appears in your view 
from your left-hand side and then moves out of your view on the 
right-hand side when you view it from a merry-go-round turning 
around in anti-clockwise direction.
Using the observations made by us while riding a merry-go-
round, let us now think. When we view from the Earth, the Sun 
appears in the East, moves across the sky from the East to the West 
and disappears in the West. Does it indicate that the Sun is moving 
in the sky? Or might it be that the Earth itself is turning around 
and the Sun just appears to move?
The fact is that the Sun appears to be moving because we view 
it from the Earth, which is turning around itself. 
Chapter 12.indd   170 4/3/2025   4:57:12 PM
Earth, Moon, and the Sun
171
In which way is the Earth turning around itself? To visualise 
this, let us recall some of the objects which turn around themselves. 
Have you watched a top spinning around its spindle (Fig. 12.2a)? 
Or a spinning fan (Fig. 12.2b)? Or tried spinning a ball (Fig. 12.2c)? 
Fig. 12.2: (a) A spinning top (b) A spinning fan (c) A spinning ball
(a) (b)
(c)
North Pole
(NP)
Northern
Hemisphere
West
Equator
Southern
Hemisphere
South Pole
(SP)
Fig. 12.3: Rotation of the Earth
Earth's axis of 
rotation
East
In a similar manner, the Earth also spins (or 
rotates) on its own axis in space as shown in Fig. 12.3. 
The Earth’s axis of rotation passes through its 
geographic North Pole and the South Pole. The Earth 
completes one rotation in about 24 hours.
When viewed from the top of the North Pole 
(Fig. 12.3), the Earth is rotating in the anti-clockwise 
direction, that is, from West to East.
Let us try to understand this with the help of a 
globe. You have used a globe in Grade 6 to represent 
the Earth and identi? ed North Pole, South Pole, and 
Equator on it. You also learnt that its axis passed 
through its North and South poles (in the Grade 6 Social 
Science textbook Exploring Society India and Beyond).
Activity 12.2: Let us explore
? Use a globe to represent the Earth and place a small 
sticker to mark your location on it (Fig. 12.4a). 
? While viewing from above the North Pole, slowly 
rotate the globe on its axis in anti-clockwise 
direction. 
? Observe how your location turns around 
and ? nally comes back to its original position 
completing one rotation.
Rotation is the motion of an object 
in which all its parts move in circles 
around an imaginary line that passes 
through it. This line is called the axis 
of rotation.
in which all its parts move in circles 
around an imaginary line that passes 
through it. This line is called the axis 
of rotation.
D
IVE
EEPER
Fig. 12.4(a): Using a globe to 
understand rotation of the Earth
Sticker 
Chapter 12.indd   171 4/3/2025   4:57:14 PM
Page 4


Earth, Moon, and 
the Sun
12
Earth, Moon, and 
the Sun
12
One morning in Kanniyakumari, Tamil Nadu, 12-year-old 
Rashmika was eagerly cycling to school. She was excited. That was 
the day her science teacher had dedicated a class for students to 
share and try to explain interesting observations.
Rashmika had been noticing that the coconut tree shadows 
were long in the morning but shorter in the afternoon on her 
way back. She thought about it and decided that the size of the 
shadows changed because the Sun moved across the sky during 
the day. But she also remembered learning that the Earth moved 
around the Sun (in chapter ‘Beyond Earth’ in the Grade 6 Science 
textbook Curiosity) so she was puzzled. She wondered — does the 
Sun move in the sky? Or does the Earth move?
Chapter 12.indd   169 4/3/2025   4:57:11 PM
Curiosity  Textbook of Science  Grade 7
170
12.1 Rotation of the Earth
You might have also noticed that the Sun rises in the East and sets in 
the West. Have you ever wondered why? Let us try to understand 
why. Have you ever enjoyed riding a merry-go-round at a park or 
at your school? Let us go back to riding a merry-go-round!
Activity 12.1: Let us explore
? Sit on a merry-go-round facing towards the outer side as 
shown in Fig. 12.1.
Fig. 12.1: A girl observing objects around 
her while riding a merry-go-round
? Ask someone to turn the merry-go-
round slowly in the anti-clockwise 
direction as shown in Fig. 12.1. While 
you are sitting on the moving merry-
go-round, look around you. Do the 
objects around you appear to be 
moving? In which direction do they 
appear to be moving? 
While you turn in the anti-clockwise 
direction, the objects appear to turn 
around you in the opposite direction, that 
is, in the clockwise direction.
? Now ? x your gaze at a particular tree 
(or a building) ahead of you while 
sitting on the merry- go-round turning 
around in anti-clockwise direction.
In which direction do you ? nd the tree turning around you? Is 
it in your view all the time?
The tree appears to turn around you in the opposite direction, 
that is, the clockwise direction. The tree appears in your view 
from your left-hand side and then moves out of your view on the 
right-hand side when you view it from a merry-go-round turning 
around in anti-clockwise direction.
Using the observations made by us while riding a merry-go-
round, let us now think. When we view from the Earth, the Sun 
appears in the East, moves across the sky from the East to the West 
and disappears in the West. Does it indicate that the Sun is moving 
in the sky? Or might it be that the Earth itself is turning around 
and the Sun just appears to move?
The fact is that the Sun appears to be moving because we view 
it from the Earth, which is turning around itself. 
Chapter 12.indd   170 4/3/2025   4:57:12 PM
Earth, Moon, and the Sun
171
In which way is the Earth turning around itself? To visualise 
this, let us recall some of the objects which turn around themselves. 
Have you watched a top spinning around its spindle (Fig. 12.2a)? 
Or a spinning fan (Fig. 12.2b)? Or tried spinning a ball (Fig. 12.2c)? 
Fig. 12.2: (a) A spinning top (b) A spinning fan (c) A spinning ball
(a) (b)
(c)
North Pole
(NP)
Northern
Hemisphere
West
Equator
Southern
Hemisphere
South Pole
(SP)
Fig. 12.3: Rotation of the Earth
Earth's axis of 
rotation
East
In a similar manner, the Earth also spins (or 
rotates) on its own axis in space as shown in Fig. 12.3. 
The Earth’s axis of rotation passes through its 
geographic North Pole and the South Pole. The Earth 
completes one rotation in about 24 hours.
When viewed from the top of the North Pole 
(Fig. 12.3), the Earth is rotating in the anti-clockwise 
direction, that is, from West to East.
Let us try to understand this with the help of a 
globe. You have used a globe in Grade 6 to represent 
the Earth and identi? ed North Pole, South Pole, and 
Equator on it. You also learnt that its axis passed 
through its North and South poles (in the Grade 6 Social 
Science textbook Exploring Society India and Beyond).
Activity 12.2: Let us explore
? Use a globe to represent the Earth and place a small 
sticker to mark your location on it (Fig. 12.4a). 
? While viewing from above the North Pole, slowly 
rotate the globe on its axis in anti-clockwise 
direction. 
? Observe how your location turns around 
and ? nally comes back to its original position 
completing one rotation.
Rotation is the motion of an object 
in which all its parts move in circles 
around an imaginary line that passes 
through it. This line is called the axis 
of rotation.
in which all its parts move in circles 
around an imaginary line that passes 
through it. This line is called the axis 
of rotation.
D
IVE
EEPER
Fig. 12.4(a): Using a globe to 
understand rotation of the Earth
Sticker 
Chapter 12.indd   171 4/3/2025   4:57:14 PM
Curiosity  Textbook of Science  Grade 7
172
Fig. 12.4(b): Using a globe and a torchlight to 
understand day and night
? Use a torch to represent the Sun. Go 
to a relatively dark room to carry 
out the further steps of the activity.
? Now, shine light from the torch 
placed at some distance, say 
1.5 metres, on the globe as shown in 
Fig. 12.4b. Do you notice how half 
of the globe receives the light from 
the torch, while the other half stays 
dark? 
It is day time in that half of the globe 
which receives light, and night time in 
the other half.
? In India, sunrise ? rst occurs in 
the eastern part and then in other 
parts. While looking at the eastern part of India on the globe, 
rotate the globe in one direction and then in the opposite 
direction. What is the direction of rotation when light falls on 
the eastern part of India ? rst? 
The light falls on the eastern part of India ? rst when the globe 
rotates from West to East with respect to the North-South axis of 
the globe. 
? Now while rotating the globe from West to East, observe your 
location on the Earth. Does it go through a cycle of day and 
night?
Sunrise occurs as your location moves into light and sunset 
occurs as it moves into darkness.
The Earth’s rotation from West to East causes the day-night 
cycle. As shown in Fig. 12.5, the side facing the Sun experiences 
daytime, while the other side is dark and experiences night.
Fig. 12.5: Sunlight falls on half of the Earth’s surface
NP
Sunrays
Earth's axis 
of rotation
Let us now further explore 
to understand how day and 
night occur on the Earth due 
to its rotation.
Chapter 12.indd   172 4/3/2025   4:57:15 PM
Page 5


Earth, Moon, and 
the Sun
12
Earth, Moon, and 
the Sun
12
One morning in Kanniyakumari, Tamil Nadu, 12-year-old 
Rashmika was eagerly cycling to school. She was excited. That was 
the day her science teacher had dedicated a class for students to 
share and try to explain interesting observations.
Rashmika had been noticing that the coconut tree shadows 
were long in the morning but shorter in the afternoon on her 
way back. She thought about it and decided that the size of the 
shadows changed because the Sun moved across the sky during 
the day. But she also remembered learning that the Earth moved 
around the Sun (in chapter ‘Beyond Earth’ in the Grade 6 Science 
textbook Curiosity) so she was puzzled. She wondered — does the 
Sun move in the sky? Or does the Earth move?
Chapter 12.indd   169 4/3/2025   4:57:11 PM
Curiosity  Textbook of Science  Grade 7
170
12.1 Rotation of the Earth
You might have also noticed that the Sun rises in the East and sets in 
the West. Have you ever wondered why? Let us try to understand 
why. Have you ever enjoyed riding a merry-go-round at a park or 
at your school? Let us go back to riding a merry-go-round!
Activity 12.1: Let us explore
? Sit on a merry-go-round facing towards the outer side as 
shown in Fig. 12.1.
Fig. 12.1: A girl observing objects around 
her while riding a merry-go-round
? Ask someone to turn the merry-go-
round slowly in the anti-clockwise 
direction as shown in Fig. 12.1. While 
you are sitting on the moving merry-
go-round, look around you. Do the 
objects around you appear to be 
moving? In which direction do they 
appear to be moving? 
While you turn in the anti-clockwise 
direction, the objects appear to turn 
around you in the opposite direction, that 
is, in the clockwise direction.
? Now ? x your gaze at a particular tree 
(or a building) ahead of you while 
sitting on the merry- go-round turning 
around in anti-clockwise direction.
In which direction do you ? nd the tree turning around you? Is 
it in your view all the time?
The tree appears to turn around you in the opposite direction, 
that is, the clockwise direction. The tree appears in your view 
from your left-hand side and then moves out of your view on the 
right-hand side when you view it from a merry-go-round turning 
around in anti-clockwise direction.
Using the observations made by us while riding a merry-go-
round, let us now think. When we view from the Earth, the Sun 
appears in the East, moves across the sky from the East to the West 
and disappears in the West. Does it indicate that the Sun is moving 
in the sky? Or might it be that the Earth itself is turning around 
and the Sun just appears to move?
The fact is that the Sun appears to be moving because we view 
it from the Earth, which is turning around itself. 
Chapter 12.indd   170 4/3/2025   4:57:12 PM
Earth, Moon, and the Sun
171
In which way is the Earth turning around itself? To visualise 
this, let us recall some of the objects which turn around themselves. 
Have you watched a top spinning around its spindle (Fig. 12.2a)? 
Or a spinning fan (Fig. 12.2b)? Or tried spinning a ball (Fig. 12.2c)? 
Fig. 12.2: (a) A spinning top (b) A spinning fan (c) A spinning ball
(a) (b)
(c)
North Pole
(NP)
Northern
Hemisphere
West
Equator
Southern
Hemisphere
South Pole
(SP)
Fig. 12.3: Rotation of the Earth
Earth's axis of 
rotation
East
In a similar manner, the Earth also spins (or 
rotates) on its own axis in space as shown in Fig. 12.3. 
The Earth’s axis of rotation passes through its 
geographic North Pole and the South Pole. The Earth 
completes one rotation in about 24 hours.
When viewed from the top of the North Pole 
(Fig. 12.3), the Earth is rotating in the anti-clockwise 
direction, that is, from West to East.
Let us try to understand this with the help of a 
globe. You have used a globe in Grade 6 to represent 
the Earth and identi? ed North Pole, South Pole, and 
Equator on it. You also learnt that its axis passed 
through its North and South poles (in the Grade 6 Social 
Science textbook Exploring Society India and Beyond).
Activity 12.2: Let us explore
? Use a globe to represent the Earth and place a small 
sticker to mark your location on it (Fig. 12.4a). 
? While viewing from above the North Pole, slowly 
rotate the globe on its axis in anti-clockwise 
direction. 
? Observe how your location turns around 
and ? nally comes back to its original position 
completing one rotation.
Rotation is the motion of an object 
in which all its parts move in circles 
around an imaginary line that passes 
through it. This line is called the axis 
of rotation.
in which all its parts move in circles 
around an imaginary line that passes 
through it. This line is called the axis 
of rotation.
D
IVE
EEPER
Fig. 12.4(a): Using a globe to 
understand rotation of the Earth
Sticker 
Chapter 12.indd   171 4/3/2025   4:57:14 PM
Curiosity  Textbook of Science  Grade 7
172
Fig. 12.4(b): Using a globe and a torchlight to 
understand day and night
? Use a torch to represent the Sun. Go 
to a relatively dark room to carry 
out the further steps of the activity.
? Now, shine light from the torch 
placed at some distance, say 
1.5 metres, on the globe as shown in 
Fig. 12.4b. Do you notice how half 
of the globe receives the light from 
the torch, while the other half stays 
dark? 
It is day time in that half of the globe 
which receives light, and night time in 
the other half.
? In India, sunrise ? rst occurs in 
the eastern part and then in other 
parts. While looking at the eastern part of India on the globe, 
rotate the globe in one direction and then in the opposite 
direction. What is the direction of rotation when light falls on 
the eastern part of India ? rst? 
The light falls on the eastern part of India ? rst when the globe 
rotates from West to East with respect to the North-South axis of 
the globe. 
? Now while rotating the globe from West to East, observe your 
location on the Earth. Does it go through a cycle of day and 
night?
Sunrise occurs as your location moves into light and sunset 
occurs as it moves into darkness.
The Earth’s rotation from West to East causes the day-night 
cycle. As shown in Fig. 12.5, the side facing the Sun experiences 
daytime, while the other side is dark and experiences night.
Fig. 12.5: Sunlight falls on half of the Earth’s surface
NP
Sunrays
Earth's axis 
of rotation
Let us now further explore 
to understand how day and 
night occur on the Earth due 
to its rotation.
Chapter 12.indd   172 4/3/2025   4:57:15 PM
Earth, Moon, and the Sun
173
Now imagine that you are standing on the Equator on the 
Earth and watching the sky during one rotation of the Earth while 
it rotates from West to East. What will you observe? Will your 
observation be the same as that of the girl shown in Fig. 12.6? observation be the same as that of the girl shown in Fig. 12.6? 
Fig. 12.6: A girl on the rotating Earth viewing the Sun from the Equator 
2. Around noon, I have rotated to a new 
position where the Sun is now over my head.
3. By evening, I have 
rotated further. The Sun 
has started to disappear 
from my view to the left 
from the West. The stars 
will now become visible 
in the night sky.
1. I am facing North 
and my back is to the 
South. The morning Sun 
appears in my view to 
my right in the East.
East West
East West
East West
Due to the rotation of the Earth, the Sun appears to rise in the 
eastward direction, move across the sky from the East to the West 
and set in the westward direction (Fig. 12.6). Then the night begins 
and the stars become visible in the sky.
FASCINATING FACTS
In an earlier chapter ‘Measurement of Time and 
Motion’, you learnt how the scientist Galileo 
discovered an important property of a pendulum, 
and in the seventeenth century, another scientist, 
Huygens, used that property to make pendulum 
clocks that measured time. In the middle of 
nineteenth century, another scientist, Leon 
Foucault, used a long pendulum to give the ? rst 
simple demonstration of the Earth’s rotation. The 
pendulum, known as a Foucault pendulum in his 
honour, consists of a long string with a heavy bob, 
suspended from a high ceiling.
A Foucault pendulum with a length of 22 metres 
has been hung from a skylight in the Constitution 
Hall of the new Parliament building in New Delhi, 
India. It symbolises the integration of the idea of 
India with the vastness of the cosmos.
pendulum, known as a Foucault pendulum in his 
honour, consists of a long string with a heavy bob, 
suspended from a high ceiling.
has been hung from a skylight in the Constitution 
Hall of the new Parliament building in New Delhi, 
India. It symbolises the integration of the idea of 
India with the vastness of the cosmos.
Chapter 12.indd   173 4/3/2025   4:57:16 PM