Download Unit - 2 The Earth and Its History- Students` Manual - CBSE

CLASS
CBSE-i
GEOGRAPHY
VI
Unit-2
THE EARTH AND
ITS HISTORY
STUDENTS’ MANUAL
Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110 092 India
CBSE-i
GEOGRAPHY
THE EARTH AND
ITS HISTORY
STUDENTS’ MANUAL
CLASS
VI
Unit-2
Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110 092 India
The CBSE-International is grateful for permission to reproduce
and/or translate copyright material used in this publication. The
acknowledgements have been included wherever appropriate and
sources from where the material has been taken duly mentioned. In
case anything has been missed out, the Board will be pleased to rectify
the error at the earliest possible opportunity.
All Rights of these documents are reserved. No part of this publication
may be reproduced, printed or transmitted in any form without the
prior permission of the CBSE-i. This material is meant for the use of
schools who are a part of the CBSE-International only.
Preface
This International Curriculum initiated by Central Board of Secondary Education - (CBSE) is a progressive step in making the
educational content and methodology more sensitive and responsive to the global needs. It signifies the emergence of a fresh
thought process in imparting a curriculum which would restore the autonomy of the learner to pursue the learning process in
harmony with the existing personal, social and cultural ethos.
The Central Board of Secondary Education has been providing support to the academic needs of the learners worldwide. It has
about 12500 schools affiliated to it and over 158 schools situated in more than 23 countries. The Board has always been conscious
of the varying needs of the learners and has been working towards contextualizing certain elements of the learning process to the
physical, geographical, social and cultural environment in which they are engaged. The International Curriculum being
designed by CBSE-i, has been visualized and developed with these requirements in view.
The nucleus of the entire process of constructing the curricular structure is the learner. The objective of the curriculum is to
nurture learner autonomy, given the fact that every learner is unique. The learner has to understand, appreciate, protect and
build on values, beliefs and traditional wisdom, make the necessary modifications, improvisations and additions wherever and
whenever necessary.
The recent scientific and technological advances have thrown open the gateways of knowledge at an astonishing pace. The
speed and methods of assimilating knowledge have put forth many challenges to educators, forcing them to rethink their
approaches for knowledge processing by their learners. In this context, it has become imperative for them to incorporate those
skills which will enable young learners to become 'life long learners'. The ability to stay current, to upgrade skills with emerging
technologies, to understand the nuances involved in change management and the relevant life skills have to be a part of the
learning domains of the global learners. The CBSE-i curriculum has taken cognizance of these requirements.
The CBSE-i aims to carry forward the basic strength of the Indian system of education while promoting critical and creative
thinking skills, effective communication skills, interpersonal and collaborative skills along with information and media skills.
There is an inbuilt flexibility in the curriculum, as it provides a foundation and an extension curriculum, in all subject areas to
cater to the different pace of learners.
The CBSE introduced classes I and X in the session 2010-11 as a pilot project in schools. It was further extended to classes II, VI
and X in the session 2011-12. In the seesion 2012-13, CBSE-i is going to enter in third year with classes III, VII and XI. The focus of
CBSE-i is to ensure that the learner is stress-free and committed to active learning. The learner would be evaluated on a
continuous and comprehensive basis consequent to the mutual interactions between the teacher and the learner. There are some
non-evaluative components in the curriculum which would be commented upon by the teachers and the school. The objective of
this part or the core of the curriculum is to scaffold the learning experiences and to relate tacit knowledge with formal
knowledge. This would involve trans-disciplinary linkages that would form the core of the learning process. Perspectives,
SEWA (Social Empowerment through Work and Action), Life Skills and Research would be the constituents of this 'Core'. The
Core skills are the most significant aspects of a learner's holistic growth and learning curve.
The International Curriculum has been designed keeping in view the foundations of the National Curricular Framework (NCF
2005) NCERT and the experience gathered by the Board over the last seven decades in imparting effective learning to millions of
learners, many of whom are now global citizens.
The Board does not interpret this development as an alternative to other curricula existing at the international level, but as an
exercise in providing the much needed Indian leadership for global education at the school level. The International Curriculum
would evolve building on learning experiences inside the classroom over a period of time. The Board while addressing the
issues of empowerment with the help of the schools' administering this system strongly recommends that practicing teachers
become skillful learners on their own and also transfer their learning experiences to their peers through the interactive platforms
provided by the Board.
I profusely thank Shri G. Balasubramanian, former Director (Academics), CBSE, Dr. Sadhana Parashar, Director (Training)
CBSE, Dr. Srijata Das, Education Officer CBSE, CBSE along with all the Officers involved in the development and
implementation of this material.
The CBSE-i website enables all stakeholders to participate in this initiative through the discussion forums provided on the
portal. Any further suggestions for modifying any part of this document are welcome.
Vineet Joshi
Chairman , CBSE
Advisory
Shri Vineet Joshi, Chairman, CBSE
Dr. Sadhana Parashar, Director (Training), CBSE
Ideators VI-VIII
Ms. Aditi Mishra
Ms. Guneet Ohri
Ms. Sudha Ravi
Ms. Himani Asija
Ms. Neerada Suresh
Dr. Rajesh Hassija
Ms. Preeti Hans
Ms. Neelima Sharma
Ms. Gayatri Khanna
Ms. Urmila Guliani
Ms. Anuradha Joshi
Mrs. Sonali Sinha
Conceptual Framework
Shri G. Balasubramanian, Former Director (Acad), CBSE
Ms. Abha Adams, Consultant, Step by Step, School, Noida
Dr. Sadhana Parashar, Director (Training), CBSE
Ms. Charu Maini
Dr. Usha Sharma
Prof. Chand Kiran Saluja
Dr. Meena Dhani
Ms. Vijay Laxmi Raman
Mrs. Avanita Bir
Ms. Malini Sridhar
Ms. Leela Raghavan
Dr. Rashmi Sethi
Ms. Seema Rawat
Ms. Suman Nath Bhalla
Prof. Om Vikas
Material Production Groups: Classes VI-VIII
English :
Ms. Neha Sharma
Ms. Dipinder Kaur
Ms. Sarita Ahuja
Ms. Gayatri Khanna
Ms. Preeti Hans
Ms. Rachna Pandit
Ms. Renu Anand
Ms. Sheena Chhabra
Ms. Veena Bhasin
Ms. Trishya Mukherjee
Ms. Neerada Suresh
Ms. Sudha Ravi
Ms. Ratna Lal
Ms. Ritu Badia Vashisth
Ms. Vijay Laxmi Raman
Core - Research
Ms. Renu Anand
Ms. Gayatri Khanna
Dr. N K Sehgal
Ms. Anita Sharma
Ms. Rashmi Kathuria
Ms. Neha Sharma
Ms. Neeta Rastogi
Ms. Manjushtha Bose
Mathematics :
Dr. Ram Avtar
Mr. Mahendra Shankar
Chemistry
Ms. Poonam Kumar Mendiratta Ms. Deepa Gupta
Ms. Gayatri Chowhan
Ms. Rashmi Sharma
Ms. N Vidya
Ms. Kavita Kapoor
Ms. Divya Arora
Ms. Mamta Goyal
Ms. Chhavi Raheja
Physics :
Ms. Vidhu Narayanan
Hindi:
Ms. Meenambika Menon
Mr. Akshay Kumar Dixit
Ms. Patarlekha Sarkar
Ms. Veena Sharma
Ms. Neelam Malik
Ms. Nishi Dhanjal
Biology:
Ms. Kiran Soni
Mr. Saroj Kumar
CORE-SEWA
Ms. Rashmi Ramsinghaney
Ms. Vandna
Ms. Prerna Gosain
Ms. Nishtha Bharati
Ms. Seema Kapoor
Mr. Manish Panwar
Ms. Seema Bhandari
Ms. Vikram Yadav
Ms. Seema Chopra
Ms. Monika Chopra
Ms. Reema Arora
Ms. Jaspreet Kaur
Ms. Neha Sharma
Ms. Preeti Mittal
ICT
Ms. Shipra Sarcar
Ms. Leela Raghavan
Mr. Yogesh Kumar
Ms. Varsha Manku
Dr. K L Chopra
Ms. Nancy Sehgal
Ms. Purvi Srivastava
Ms. Babita Mahajan
Ms. Ritu Arora
Ms. Swati Panhani
Ms. Chanchal Chandna
Geography:
Ms. Suparna Sharma
Ms. Aditi Babbar
History :
Ms. Leeza Dutta
Ms. Kalpana Pant
Ms. Ruchi Mahajan
Political Science:
Ms. Kanu Chopra
Ms. Shilpi Anand
Economics :
Ms. Leela Garewal
Ms. Anita Yadav
CORE-Perspectives
Ms. Madhuchhanda
Ms. Varsha Seth
Ms. Neha Sharma
Chief Co-ordinator : Dr. Srijata Das, EO
Coordinators:
Ms. Sugandh Sharma, EO
Dr Rashmi Sethi, EO
Ms. S. Radha Mahalakshmi, E O Ms. Madhuchhanda, RO (Inn)
Mr. Navin Maini, RO (Tech) Shri Al Hilal Ahmed, AEO Shri R. P. Singh, AEO
Ms. Anjali Chhabra, AEO
Ms. Neelima Sharma,
Consultant (English)
Mr. Sanjay Sachdeva, SO
Sh. R. P. Sharma
Consultant (Science)
Ms. Reema Arora
Consultant (Chemistry)
Contents
The Universe:
1
Its Definition and Evolution
The Big Bang Theory:
2
An Explanation Relating to Evolution of Universe
The Solar System:
6
The Solar Family and a Comparative Study of
Different Planets
Continent Building of the Earth:
Its Evolution and its Present form
Formation of Continents and their Location
The Earth as Life-bearing Planet:
The Conditions that Separates it from other
Planets of the Solar System
17
UNIT-II
THE EARTH AND ITS HISTORY
Introduction
Halley‘s Comet, Ursa Major, North Star, Milky Way, the moon and the sun, all have something
in common – they are all part of the Universe. All matter that was condensed into an
unimaginable dense sphere smaller than a ‗full stop‘ exploded and expanded into the limitless
Universe subsequently various celestial bodies were formed.
Starry nights have attracted everybody. Numerous questions about their shining in the sky,
their existence, and the end of the sky have always been asked. The dynamic nature of
Universe and various bodies that constitute it have been a subject of study since time
immemorial and continue to hold vivid human interest in the contemporary world.
The Earth and Its History – An Overview
The Universe began with a Big Bang about 15 billion years ago. An explosion followed by an
expansion formed the history of the Universe. A large number of hypothesis were put forth by
different philosophers and scientists regarding the origin of the Universe to understand the
origin of Earth. The most popular argument regarding the origin of Universe is the Big Bang
theory also referred to as the ‗Expanding Universe Hypothesis‘.
DO YOU KNOW?
Edwin Hubble, in 1920, provided evidence that the universe is expanding. As time passes,
galaxies move further and further apart. The expansion of universe means increase in
space between the galaxies.
An alternative to this was Hoyle‘s concept of steady state. It considers the universe to be
roughly the same at any point of time.
1
The Big Bang Theory
BIG BANG – THE EXPLOSION AND EXPANSION OF UNIVERSE
We have often gazed up at the night sky in wonder, thinking: What is the connection between
the brilliant display in the sky and us, down here on the Earth?
The big bang explains the expansion of space. While many people believe that the big bang
theory refers to an explosion, it actually began with an explosion and refers to the expansion
of the universe. Most astronomers believe that all matter forming the universe existed in one
place in the form of a tiny ball. 13.7 billion years before the present a gigantic explosion,
called the Big Bang, occurred and the tiny ball exploded. Small atoms formed within minutes
of the explosion and the process of creation started (and is still carrying on even today) and
slowly, nebulae, stars, galaxies and further planets developed and we know the universe as it
is today.
While many people believe that the big bang theory refers to an explosion, it actually began
with an explosion and refers to the expansion of the universe. The universe consists of all
things that exist - stars, galaxies, planets. The origin of the Earth can be explained through
the ‗The Big Bang‘ theory.
Almost a billion years after the Big Bang stars, dust and gases clustered together to form
galaxies. The biggest galaxies are nearly as old as the universe, while smaller ones may still
be born.
The Milky Way Galaxy, which is the home of our earth and Solar System, was formed 5 billion
years after the explosion.
2
The gas and dust spinning around the gaseous core of the sun led to the formation of the
Earth and the other planets of the solar family. Hence, all the planets rotate on their axis and
revolve around the sun. The path that the planets take to go around the sun is elliptical
(oval).This path is known as its orbit.
Do it yourself - Expanding Universe
A simple experiment that will help in understanding the concept of ‗Expanding Universe‘.
Requirements:
1.
A 12 inches round latex balloon.
2.
A permanent marker
3.
Piece of string
4.
Metric ruler
Procedure:
Take a balloon and mark six dots in widely scattered locations representing the
galaxies. Measure the distance between the marked dots.
Inflate the balloon so the diameter is about 4 inches. Measure the distance
between the galaxies now and make a note of it against the earlier markings.
Inflate the balloon to a diameter of 8 inches and note your observations about the
distance between the points marked as galaxies.
Observation:
What do you observe and conclude from your findings regarding the increasing distance
between the dots as the balloon is inflated.
Conclusion:
Similarly the distance between the galaxies is also found to be increasing and thereby
universe is considered to be expanding.
The Celestial Bodies
All objects that belong to the sky are called celestial bodies. The Sun, the Moon and millions
of shining objects in the sky are all celestial bodies. They are also known as heavenly bodies.
3
THE CELESTIAL BODIES
Stars are made of burning gases. When the gases burn they release tremendous amount of
heat and light. Hence, they twinkle. The star nearest to the earth is the Sun. There are
millions of stars like our Sun.
Planets are heavenly bodies made of solid material. They do not have heat and light of their
own. They reflect the light they receive from the stars. The Earth is a planet and it receives
its heat and light from the Sun.
Asteroids: are a swarm of small bodies that revolve around the sun between the orbits of
inner and outer planets, Mars and Jupiter. CERES is the largest asteroid. They are considered
as fragments of a planet which exploded in the past.
ASTEROIDS
4
Meteors: These are countless tiny objects orbiting the sun, which are attracted by Earth‘s
gravitational force when they pass near the Earth. As these objects enter the Earth‘s
atmosphere, they are moving at tremendous speed. This causes friction. The heat thus
produced causes it to burn up before it reaches the Earth. These objects, seen as streaks of
light in the sky, are called meteors. Meteors are commonly called shooting stars.
A METEOR
Meteorites: These are large objects probably from the asteroid belt. They journey through
the Earth‘s atmosphere without being completely destroyed. Meteorite falls are not very
common but when they fall they cause a lot of damage.
DO YOU KNOW?
Origin of some celestial words:
Planet: This word comes from the Greek word ‗Planasthai‘ which means ‗to wander‘.
Satellite: This word has its root in the Latin ‗Satelles‘, which means attendant.
Solar: This word has its root in the Latin word Solaris, meaning Sun.
5
Our Solar System
Our Solar system consists now of eight planets as status of Pluto has changed to a dwarf
planet. Our Solar system is supposed to have been formed 5-5.6 billion years ago and the
planets were formed about 4.6 billion years ago.
Our solar system consists of the sun (the star), 8 planets, 63 moons, millions of smaller bodies
like asteroids and comets and huge quantity of dust-grains and gases. Out of the eight
planets, Mercury, Venus, Earth and Mars are called as the inner planets as they lie between
the Sun and the belt of asteroids the other four planets are called the outer planets.
Alternatively, the first four are called Terrestrial, meaning earth-like as they are made up of
rock and metals, and have relatively high densities.
The rest five are called Jovian or Gas Giant planets. Jovian means Jupiter-like. Most of them
are much larger than the terrestrial planets and have thick atmosphere.
Case Study
An Interactive Session with the Earth
Peter is a sixth grade student who has a keen interest in Earth science and is a vivid
reader. He has many questions that he would like know about the earth and its solar
system and decides to ask the Earth himself.
The following is the extract from his conversation.................
Peter: Hello there! I am Peter, I live on you and I think you are very beautiful. But, I don‘t
understand so many things about you.
6
Earth: Hello Peter! Why don‘t you ask me what you want to know?
Peter: I know you‘re round but how were you formed? Are there others like you? Do you
also belong to some family? And the sun? What…………………….
Earth: Hey! Hold on. One at a time, please. I‘m just a tiny speck among countless
heavenly bodies scattered through the vast universe. I also have a family which is called
the Solar System. The head of our family is the sun and our solar system consists of the
sun and everything that the sun‘s gravity can grab. That is, we‘re eight planets and we all
have our satellites (mine is the moon), and asteroids and comets and huge quantity of dust
grains and gasses. In addition to providing the gravitational glue that binds the solar
system, our massive sun supplies it with energy.
Peter: The sun is a big star, is it not?
Earth: Yes it is. It gives us heat and light as it is a ball of hot burning gases. Hydrogen and
helium are the main gases. Inside the sun‘s core, hydrogen is converted to helium. This
releases tons and tons of energy which reaches us as heat and light. Its surface
temperature is 6000*C. All of us evolved from the sun.
Peter: How many of you did you say are there?
Earth: Well, we are eight of us. All revolving around our parent, the Sun. Recently there
has been a new addition in the family.
Our Solar System
Peter: Are you all alike?
Earth: No, no! Four of us are terrestrial planets and four of us are gaseous. Can you name
us? And our satellites?
7
Peter: Yes, I‘m sure I can find out.
Earth: While you are at it you can also find out why I‘m the only one in my family which
supports life. And, we will later get back together for another conversation.
After his conversation with the earth Peter's curiosity is aroused and he finds out more
about our solar system.
Terrestrial Planets
Mercury: is closest to the Sun. Its day temperature
reaches almost 425 C. At night the temperature may drop
up to -180 C since there is no atmosphere to trap the
heat.
Life
is
not
possible
under
such
extreme
temperature conditions. The planet completes one
rotation in about 59 days and one revolution around the
Sun in about 88 days. The surface of the planet is covered
by craters caused by the impact of meteorites falling
from space.
Planet Mercury
Venus: It is about the same size as the Earth. It is
the brightest planet and is also called the ‗Morning
Star‘ and ―Evening Star‖ It is always covered by
thick clouds of poisonous gases making it difficult
for modern science to penetrate. Interestingly,
scientists have recently been able to peek through
the thick clouds and get a few glimpses of the
surface. There are numerous volcanoes and many
mountains that appear misshapen.
Earth: is the third nearest planet to the sun. The
Earth is the biggest of all the terrestrial planets.
Our planet is an oasis of life in an otherwise
desolate universe.
8
The Fiery Planet – Venus
THE EARTH – A UNIQUE PLANET
It is known as the ―watery planet‖ or the ―blue planet‖ because 70% of its surface is covered
with water. The distance from the sun is such that it is neither too hot nor too cold with an
average temperature of 14oC. Moreover the presence of atmosphere prevents extremes of
temperatures. The presence of water and air supports all forms of life.
Mars: Its red soil and pink sky gives it the name ―Red Planet‖. Mars is the fourth planet from
the sun. It is named after the Roman god of war.
Mars is referred to as the Red Planet, due to its red soil
made up of iron oxide, more commonly known as rust.
Due to its dry and dusty surface, dust storms have been
known to cover the whole planet at times. Mars is home
to Mt. Olympus Mons, perhaps one of the largest
volcanoes in our solar system. Olympus Mons is three
times taller than Mount Everest and as wide as the state
of New Mexico. Recently, scientists discovered enough
Planet Mars
water/ ice just under the surface of Mars to fill Lake Michigan twice. Interest in the
exploration and examination of the planet Mars by scientists and NASA has sparked an active
public interest in the planet about the existence of life there.
Gaseous Planets
Jupiter is by far the largest planet in our Solar System.
9
Planet Jupiter
The Red Spot
The Earth could fit inside Jupiter more than 1000 times. Jupiter is a very stormy planet.
There are storms found throughout the atmosphere, and most of the storms seem to never
end. The many different cloud formations and storms in the atmosphere also make Jupiter a
very colourful planet. Jupiter's great red spot, visible in the picture to the right, is where a
giant storm has been raging for at least 300 years. This red spot is also called "The Eye of
Jupiter" because of its shape. This storm's super hurricane winds blow across an area larger
than the Earth. Jupiter is considered a gas giant because it does not have a solid surface.
Under its atmosphere is a large liquid ocean of hydrogen and water. What lies in between
that ocean and the atmosphere? Actually, there is no in between. The atmosphere slowly gets
thicker and thicker until it becomes part of the ocean. In other words, Jupiter's ocean has no
surface on which you could float a boat. It has 16 satellites.
Saturn: It is known for its rings. In many ways, Saturn is similar to Jupiter, but it is much
smaller. It is the second largest planet in our Solar System and it is a gas giant like Jupiter.
Saturn is the least dense planet in our Solar System. It is made up of mostly hydrogen and
helium, are the two lightest elements in the universe. Saturn is so light, it does not have as
much gravity and this is why you wouldn't weigh as much on Saturn as you think you would.
Interestingly, it is believed Saturn would actually be able to float in water because the
hydrogen and helium that make up the planet are so lightweight.
10
PLANET SATURN
Uranus: Like Jupiter and Saturn, Uranus is a gas giant. But Uranus is a little different. Unlike
all the other planets and most of the moons in our Solar System, Uranus spins on its side. Can
you think? Like Saturn, the thick atmosphere of Uranus is made up of methane, hydrogen and
helium. But Uranus is an extremely cold planet. It has been called the "ice giant." It is
believed that Uranus is made up of rock and ice and has a large rocky core. Uranus has more
than 20 moons, all of which have been named.
THE ICY PLANET- URANUS
11
DO YOU KNOW?
It is believed that long ago a very large object smashed into this planet. The crash was so
powerful that it completely changed the direction of Uranus' planetary rotation. However,
a more recent theory is that the extreme tilt of Uranus' axis may have been caused by a
large moon that was slowly pulled away from the planet by another large planet long ago
when our Solar System was still new. It is thought that the gravitational pull of this moon
moving away from Uranus may have caused it to tilt on its side.
Neptune: The smallest of the four gas giants in our Solar System, Neptune's atmosphere
contains hydrogen, helium and methane. Neptune has 13 natural satellites.
AN ENIGMATIC STORMY GAS BALL – NEPTUNE
DO YOU KNOW?
Not much was known about Neptune until it was visited by the spacecraft Voyager 2 on
August 25, 1989. Voyager 2 took many pictures of the planet, and much of what we know
today about Neptune came from this single visit. It is a brilliant blue planet with a few
thin white clouds laced around its surface.
12
PLANETS-COMPARATIVE STUDY
PLANETS OF THE SOLAR SYSTEM
TIME
TO
AVERAGE
PLANET
DISTANCE
DIAMETER
FROM SUN
SPIN
TIME TO
ON
ORBITSUN (a
AXIS
year)
(a
GRAVIT
Y
(Earth =
1)
AVERAGE
TEMPERATUR
E
KNOWN
MOONS
day)
57,900,000
Mercury
km
(36,000,000
miles)
Venus
4,878 km
(3,031
miles)
108,160,000
12,104
km
km
(67,000,000
(7,521
-183 °C to
59
88 days
days
0.38
427 °C
(-297 °F to
None
800 °F)
243
days
224 days
13
0.9
480 °C
(896 °F)
None
Earth
miles)
miles)
149,600,000
12,756
23
km
km
hours
(92,960,000
(7,926
, 56
miles)
miles)
mins
227,936,640
Mars
km
(141,700,00
0 miles)
Jupiter
Saturn
Uranus
Neptune
6,794 km
(4,222
miles)
365.25 days
1
687 days
0.38
11.86 years
2.64
29 years
1.16
84 years
1.11
164.8 years
1.21
14 °C
(57 °F)
1
24
hours
, 37
-63 °C
(-81 °F)
2
mins
778,369,000
142,984
9
km
km
hours
(483,500,00
(88,846
, 55
0 miles)
miles)
mins
1,427,034,0
120,536
10
00 km
km
hours
(888,750,00
(74,900
, 39
0 miles)
miles)
mins
2,869,328,0
51,118
17
00 km
km
hours
(1,740,200,0
(31,763
, 14
00 miles)
miles)
mins
4,496,976,0
49,532
16
00 km
km
hours
(2,797,770,0
(30,779
,7
00 miles)
miles)
mins
Source: www.bobthealien.co.uk/table.htm
14
-130 °C
(-202 °F)
-130 °C
(-202 °F)
-200 °C
(-328 °F)
-200 °C
(-328 °F)
63
61
27
13
Dwarf Planets
Technology has improved so well in the last several years that we keep finding more and more
objects in our solar system! Because of this, scientists have had to come up with new
categories for objects in space. This included reclassifying Pluto as a dwarf planet, in 2006.
Pluto: It is smaller than 7 of the moons in the Solar System. It is about two-thirds smaller
than Earth's moon. Because it is so small, many scientists don't consider it a planet at all. In
1999, a group of scientists attempted to re-classify Pluto as a comet. On August 24, 2006,
Pluto's status was officially changed from planet to dwarf planet. For decades, children
have been taught in school that there are nine planets in our Solar System.
However, with this change, there are now only eight planets. Pluto got left out on its being
called a planet because Pluto orbits in the Kuiper Belt (basically the same thing as the
asteroid belt, just a little larger. It starts right outside the orbit of Neptune).
A true planet would have cleared the belt out of its orbit, but Pluto did not.
Also because of this change, there is a new category of small planets known as plutoids
Pluto revolves around the Sun in an orbit that is not exactly circular like the rest of the
planets. Rather, Pluto's orbit is more of an oval or egg shape. Because of this, Pluto will orbit
inside of Neptune's orbit, which makes Pluto closer to the Sun than Neptune at times.
UB313 Eris: The new planet in the solar system. Eris was a very important discovery in 2005.
Since it was larger than Pluto, some astronomers thought it should be considered a planet.
However, since Pluto and Eris are located in an asteroid belt, the status remains undecided.
15
Case Study
‘The Little Wanderers’
Source: 3.bp.blogspot.com
Dwarf planets are similar to planets except they don‘t clear their orbit like planets do.
There are currently five dwarf planets listed. They are: Ceres, Pluto, Eris (pronounced
ee‘-ris), MakeMake (pronounced mahkee-mah-kee), and Haumea (pronounced hah-oomayah).
This is a very exciting time. New objects in space are still being discovered! Scientists say
there will likely be more dwarf planets announced in the next few years.
What will be the name of the next dwarf planet?
What name would you choose?
Moon
It is the Earth‘s only satellite. It has no atmosphere. Therefore, there is a great difference
between the day and night temperatures. Due to lack of atmosphere there is no weather, no
clouds, no rain and no wind. There is no water on its surface. It takes about 29 days for one
rotation and 27 days in its revolution around the Sun.
Evolution of The Earth
The planet earth initially was a barren, rocky and hot object with a thin atmosphere of
hydrogen and helium. The period, between the 4,600 million years and the present, caused
the change from rocky, barren and hot earth to a beautiful planet with ample amount of
water and conducive atmosphere favouring the existence of life.
16
The Earth has a layered structure. From the outermost end of the atmosphere to the centre
of the Earth, the material that
exists
is
not
uniform.
The
atmospheric matter has the least
density. Erom the surface to deeper
depths, the 55arth‘s interior has
different zones and each of these
contains materials with different
characteristics. We have layers like
the crust, mantle and core.
During the cooling of the earth,
gases
and
water
vapour
were
released from the interior solid
earth. This started the evolution of
the present atmosphere that contains gases like nitrogen, carbon dioxide, oxygen. It can be
assumed that life began to evolve sometime 3,800 million years ago from unicellular bacteria
to the modern man.
Continent Building
The continents cover 29% of the Earth‘s
surface and remaining is under oceanic
waters. However, the position of the
continents and the water bodies have not
been the same in the past and it is a well
accepted fact they will not continue to
enjoy their present positions in time to
come. What were their positions in the
past? Why and how do they change their
positions and how do scientists know
about this. Let us find answers to these
questions with the help of following case
CONTINENTS IN GEOLOGICAL PAST
studies.
17
Case Study
Continental Drift Theory
Continental drift, geological theory that the relative positions of the continents on the
earth's surface have changed considerably through geologic time. The first detailed theory
of continental drift was put forth by German meteorologist and geophysicist Alfred
Wegener in 1912. He believed that about 275 to 175 million years ago, all the continents
were united into a vast supercontinent, which he called Pangaea. Later, Pangaea broke
into two super continental masses—Laurasia to the north, and Gondwanaland to the south.
The present continents began to split apart about 100 million years ago, drifting to their
present positions. The most popular evidence in support of this theory is the ‗Jig saw Fit‘.
The shorelines of Africa and South America facing each other have a remarkable and
unmistakable match.
18
Case Study
Theory of Plate Tectonics
Wegener could not provide an explanation of exactly what made the continents
move. News technology lead to findings which then lead to a new theory called
plate tectonics.
According to the plate tectonics theory, the uppermost mantle, along with the
overlying crust, behaves as a strong, rigid layer. This is also known as the
lithospheric plate or the tectonic plate.
A plate may be referred to as the continental plate or the oceanic plate depending
on which of the two occupy a larger portion of the plate. For example, Pacific
Plate is an oceanic plate while the North American Plate is a Continental Plate.
This theory proposes that earth‘s lithosphere is divided into seven major and some
minor plates. The seven major continents are part of these major plates.
19
GLOSSARY
Asteroid - A body smaller that a planet and made of rock, metal or other minerals.
Comet - An object composed of frozen gases and dust particles that was formed on the
outskirts of the solar system and that orbits the sun.
Galaxies- A cluster of stars, gases and dust.
Gravity - Force that keeps celestial bodies in place.
Nebula - Cloud of interstellar dust and gas.
Planet - A large body that orbits a star.
Plate – It is one of numerous rigid sections of the lithosphere. According to the plate tectonics
theory, the uppermost mantle, along with the overlying crust, behaves as a strong, rigid
layer. This layer is known as the lithosphere.
Satellites - A body that orbits a planet.
Star- A huge body made of hot luminous gases that are held together by its own gravity.
20
WORKSHEET – 1
Name of the Student:
Class:
Section:
Search the internet and collect the pictures showing various stages of the evolution of the
universe and as a group activity prepare an album using the same.
21
WORKSHEET - 2
Name of the Student:
Class:
Section:
1. Write your address showing your place in the universe using the following clues:
Your house number, name of the city, country, continent, planet and galaxy.
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
______________________________________________________
2. People have never walked on any planet besides Earth. Write a paragraph telling why you
would like to visit another planet.
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
______________________________________________________________________________
22
WORKSHEET - 3
Name of the Student:
Class:
Section:
1.
Label the given diagram of the Solar System showing planets in their respective orbits:
Here's a mnemonic to remember the order of the nine eight planets from the Sun:
"My Very Excellent Mother Just Served Us Nine Pizzas”
The first letter of each word represents a planet - Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus, Neptune and Pluto.
23
2.
Write another sentence that can help us to remember the planets in their order.
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
24
WORKSHEET - 4
Name of the Student:
Class:
Section:
You are on a spring break and your family decides to head out to Mars. Write a detailed
description for your friends back home saying what it was like there. Add pictures to make
your report more interesting:
25
WORKSHEET – 5
Name of the Student:
Class:
Section:
Study the origin of names of different planets and answer the questions that follow:
MERCURY--Named for the winged Roman god of travel because it appears to move so
swiftly.
VENUS- Roman name for the goddess of love. This planet was considered to be the
brightest and most beautiful planet or star in the heavens.
EARTH- The name Earth comes from the Indo-European base 'er,' which produced the
Germanic noun ‗ertho,‘ from the Anglo-Saxon word Erda (Erdaz), which means ground,
soil, and English 'earth.'
MARS- Named by the Romans for their god of war because of its red, bloodlike color.
JUPITER- The largest and most massive of the planets was named Zeus by the Greeks
and Jupiter by the Romans; he was the most important deity in both pantheons.
SATURN- Saturn was the Roman name for the Greek Cronos, god of farming and the
father of Zeus/Jupiter.
URANUS- Uranus was named for the Greek god of the sky.
NEPTUNE- Neptune, a blue planet, was named for the Roman god of the sea
1.
Is there any similarity in the names of the planets?
____________________________________________________________________________
__________________________________________________________________________
2.
Which is the only planet in the solar system, whose name is not derived from the Greek
or Roman mythology?
26
____________________________________________________________________________
__________________________________________________________________________
3.
Can you find different names of Earth in other languages?
____________________________________________________________________________
__________________________________________________________________________
27
WORKSHEET – 6
Name of the Student:
Class:
Section:
Calculate your Weight on Other planets
1.
Mercury is the smallest planet, and the planet closest to the sun.
The gravity of Mercury is 38% of Earth's gravity.
To calculate your weight on Mercury, multiply your weight by 0.38.
_____________ __________ x _____________ = __________ ___________
2.
Venus is known as the ―Cloudy Planet‖ because it is covered with thick, yellow clouds.
The gravity of Venus is 90% of Earth's gravity.
To calculate your weight on Venus, multiply your weight by 0.9.
_____________ ___________ x _______________ = ____________ ___________
3.
Mars is known as the ―Red Planet‖ because the soil is filled with orange-red particles.
The gravity of Mars is 38% of Earth's gravity.
To calculate your weight on Mars, multiply your weight by 0.38.
____________ ___________ x ______________ = ___________ ___________
4.
Jupiter has more moons than any other planet. So far, scientists have discovered 63!
The gravity of Jupiter is 234% of Earth's gravity.
To calculate your weight on Jupiter, multiply your weight by 2.34.
__________ ___________ x ______________ = ___________ ___________
28
5.
Saturn is known as the ―Ringed Planet‖ because it has colourful rings made of rock and
ice.
The gravity of Saturn is 108% of Earth's gravity.
To calculate your weight on Saturn, multiply your weight by 1.08.
_____________ ___________ x _______________ = ____________ __________
6.
Uranus spins sideways. It's North Pole and South Pole is on the sides.
The gravity of Uranus is 80% of Earth's gravity.
To calculate your weight on Uranus, multiply your weight by 0.80.
______________ _________ x ______________ = __________ ___________
29
WORKSHEET – 7
Name of the Student:
Class:
Section:
An extract......
On August 24, 2006, the International Astronomical Union (IAU) formally
downgraded Pluto from an official planet to a "dwarf planet". According to the
new rules, a planet mus ...
1. orbit around the Sun
2. have sufficient mass for its self-gravity to overcome rigid body forces to
take on a nearly round shape
3. have cleared other objects in its orbital path around the Sun
(i.e., so there are no similar objects at roughly the same distance from the
Sun)
Pluto failed the third criteria - it orbits among the icy wrecks of the Kuiper Belt
and is really "just" one of many Kuiper Belt Objects (KBOs). Eris and Ceres (in the
asteroid belt) are the other two members of this dwarf planet classification
Read the above given extract and answer the following questions:
1.
What makes Pluto different from the other planets of the solar system according to the
new guidelines given by IAU?
____________________________________________________________________________
____________________________________________________________________________
2.
Imagine Pluto is given a chance to represent his case in the ‗Court of Planets‘. Can you
help him to put together an argument in support of retaining his planet status?
____________________________________________________________________________
____________________________________________________________________________
30
WORKSHEET – 8
Name of the Student:
Class:
Section:
My Planet Diary
1.
Name: ______________________________________________
(Write the name of your planet on this line)
Draw or paste a large picture of your planet in the box given below.
31
2.
Time taken by my planet to orbit the sun. _____________________
3.
How my planet was named? _____________________________________
4.
Time taken by the moon to obit my planet. ________________________________
5.
Nature of my planet - gas or rock? ________________________________________
6.
My planet is known for ________________________________________________
(Describe a unique feature of your planet)
7.
Here are five interesting facts about my planet.
1)
_____________________________________________________________________
2)
_____________________________________________________________________
3)
_____________________________________________________________________
4)
_____________________________________________________________________
5)
_____________________________________________________________________
32
RESOURCES

Social Science Text Book Class 6_ NCERT

A Text Book of Geography 6 by Rita Rajen

http://cp.astate.edu/neapartnership/Framework%20Lessons/grade6earth.htm

http://www.sciencenetlinks.com/earthscience/

http://www.windows2universe.org

All images are from ‗Google images‘

http://www.google.co.in/imgres?imgurl=http://www.glogster.com/media/5/20/8/3/
20080338.jpg&imgrefurl=http://www.glogster.com/glog.php%3Fglog_id%3D11420054%
26scale%3D54%26isprofile%3Dtrue&h=377&w=396&sz=24&tbnid=8CzsDZXBR2jPiM:&tbnh
=118&tbnw=124&prev=/images%3Fq%3Dplanet%2Bmars&zoom=1&q=planet+mars&hl=en
&usg=__DSJKx0mS_fcOjtN9FazCMnN3Yk=&sa=X&ei=Yv6TTaigIo3xrQfnrpXxCw&ved=0CB8Q9QEwAg
33
CENTRAL BOARD OF SECONDARY EDUCATION
Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110 092 India