THE EARTH AND ITS HISTORY

CLASS CBSE-i GEOGRAPHY VI Unit-2 THE EARTH AND ITS HISTORY STUDENTS’ MANUAL Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110 092 Ind...
Author: Vernon Wilson
1 downloads 4 Views 3MB Size
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

Suggest Documents