UNIT UNIVERSE AND SPACE

EXPLORATION
Structure
6.1 Introduction

6.2 Objectives

6.3 Origin of the Universe

6.4 Universe and its Dimensions

6.5 Organisation of Earth System

6.6 Minerals and Coal Deposits

6.7 Solar System

6.8 Stars and Life History of Stars

6.9 Galaxies and their Origin

6.10 Satellite and Space Exploratio~~

6.11 Let Us Sum Up

6.12 Unit-end Exercises

6.13 Answers to Check Your Progress

6.14 Suggested Readings

6.1 INTRODUCTION
Whenever we look at the sky on a dark night we can see a cluster of stars. Out of these
stars some are very bright and large in size while some are very dull and small. Some
stars form groups with certain recognizable shapes.

You can might have observed some stars always at fixed positions but some stars like
objects keep on changing their positions these are called planets. Scientists all over the
world study these various characteristics of stars by using telescopes, spectroscopes,
spectrograph, radio, telescopes and satellites.

One should have experience of this field, to understand the relative motion of heavenly
bodies in the sky. However, you can see the sky at night to get first hand experience of
movement of stars, planets and constellations. In order to understand the movements of
'Phases of Moon', a simple model can be prepared. Artificial satellites have been used
effectively to know about the heavenly bodies. The advancement in space voyage has
opened a new dimension of activities to study the universe. We hope that exploration of
inter- sateller space through man-made space vehicles would help in obtaining more and
more knowledge about universe. In this unit, you will get some idea of nebula, galaxies,
inter galatic space, satellar evolution and origin of universe.

Further, present unit, -will arouse curiosity for further study of this challenging field,
I especially, in view of the fact, that the understanding of the structure and origin is some
30 what baffling as per the latest data.
 Universe and Space
I 6.2 OBJECTIVES Exploration
I
1 After going through this unit, you will be able to:
identify different components of the universe;
classify heavenly bodies into differentcategories;
explain different theories of origin of universe;

I
I
design self-assessment questions and activities based on our 'universe and earth
system';
develop manipulative skills and innovative skills to teach this particular topic;
I
possess detailed knowledge about solar system and motion of planets;
familiar with the origin of stars and energy generation in stars;
+ m i b e the mechanism of launching a satellite; and
understand about the importance of artificial satellite.

ORIGIN OF THE UNIVERSE

I Main Concepts

i) The universe originated from unknown cosmological explosion.

i The universe is expanding in all directions. This fact is supported by Doppler's red
shift.
Teaching-Learning Process
!
I The teacher /an give brief history of the universe
I
15-20 billion years ago, the whole universe was concentrated at a point in space. Due to
a tremendous cosmological explosion, different fragments were formed which are still
moving away from each other. Our universe consists of billions of galaxies and each
galaxy consists of thousand billions of stars. On the large distance scales of lo8-lo9 light
years, distribution of the galaxies seem to be quite uniform.
Various theories have been put forward to explain to origin of the universe.
The Big Bang Theory: According to this theory the whole universe originated from a
single point due to cosmological explosion as a result various components of the universe
were produced. A model can be shown in the class to give the idea to expanding
universe. Dots or points painted on the surface of an expanding balloon can depict a
picture of the expanding universe.

rn
Deflated balloon
3 A A A

inflated hlloon

Fig. 6.1

Hubble observed and photographed the galaxies outside the Milky Way and proved that
galaxies are moving away from one another. This view is also supported by astronomers
Teaching ~~~~~i~~ of recording the frequencies of the light coming from Inany galaxies they found that these
Concepts in Science frequencies to be less then those expected and shifted towards red light. This is known
has the red shift. The reason for this shift is the Doppler effect. It states that decrease in
the frequency of wave received by an observer i.e. Earth, is caused by the motion of the
source i.e. galaxy, away from the observer. Thus, the Doppler red shift also proves that
universe is expanding. Fig. 6.2 diagramnlatically illustrated the situation the speed ofthe
galaxies increases as their distance increases from our Earth.

Fig. 6.2: Movement of galaxies in universe

Quasars are very small star like outernlost objects of the universe and are moving away
with 90% the velocity of light. These are cosmic source of light and radio waves. Their
existence also supports the Big Bang Theory.
Pulsating Theory: At present the galaxies are moving away but they also experience
cumulative gravitational force. If the mass-energy content is above a critical value; the
galaxies will slow down under the influence ofthe gravitational force. After sometime the
galaxies will start moviiig toward each other and will be again start concentrating at a
point. Again, the cosmological explosion will occur and universe will be created again.
According to some Astronomers, this process will repeat again and again. This theory is
called Pulsating Theory.
The Steady State Theory: Some part of tlle observation of the sky revealed that the
density of the universe appears to be constant. We are living in a homogeneous universe
in which all points are alike. According to this theory new galaxies are formed in the
empty space created due to the outward motion of the galaxies. It follows that for the
density to remain constant new matter must be created at the same rate at which the
expansion would decrease the density.
By and large, the evidences available are in favour of Big Bang theory.
Methodology used: In this chapter the field study-cum-enquiry method is used. Visit to
planetarium will enable you to make the students to gain better knowledge of related
concepts Big Bang theory is explained by the demonstration shown in Fig. 6.1.
Teaching aids: Charts, trarisparencies and films and opaque projection.

Check Your Progress

Notes: a) Write your answers in the space given below.
b) Cornpare your answers with those given at the end of the unit.
1) What is meant by the term Universe?
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 Universe and Space
2) What is the age of the Universe? Exploration
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3) Distinguish between a star and a planet.'
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1 4) What is a galaxy?
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5) How many galaxies are there in the Universe?
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6) What is the appropriate mass of the Universe?
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6.4 UNIVERSE AND ITS DIMENSIONS

Main Concepts
i) Dimensions of the Universe are of the order of billions of light years.
ii) Inter-galactic distances have a magnitude of millions of light years.
Teaching-Learning Process
Astronomy is the oldest branch of science. It is based on meticulous observations and
analysis. ofthe study of the Universe. It is also the study about the position, motion, size,
origin and properties of objects around our earth and far- far way from our solar system.
The sun is only one of the billions and billions of stars that exist in the universe. These
stars are uniformly distributed in space in huge clusters. These Clusters of Stars, dust
particles and gaseous matter is called a galaxy. There are billions of galaxies in the universe
which are moving away. Hubble measured this distance up to lo9light years. This means
that dimensions ofthe universe are larger than this limit. You might be interested in some
interesting facts about galaxy. Can you believe the size of galaxies may be 1000.000 light
years or larger and the nearest galaxy to the one that we live in is 2x106light years away!
 /

Teaching Learning of The distance can be scaned by Radio telescope up to l o i 0light year. The inter-galactic
Concepts in Science distances have a magnitude of millions of light years. The distance of various galaxies
are given in Fig. 6.2.

Hubble measured the velocities of stars at different distances which is indicated in the
following Fig. 6.3.

W i n c e ln 10' light years +

Fig. 6.3

Fig. 6.3 clearly indicated that the more the galaxy's distance from earth, the faster it's
moving away from the earth.

Methodology used: Discussion method. The lesson developed by discussion method.

The lesson will become Inore interesting if pupils response are adopted in development of
lesson.

Teaching aid: Charts, transparencies, and films.

Check Your Progress

Notes: a) Write your answers in the space given below.
b) Compare your answers with those given at tlie end of the unit.
7) Define one light year?
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8) What is age of our Universe?
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9) Define quasars?
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 Universe and Space
10) What is size of our Universe? Exploration
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I I) What is the length of Milky Way?

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12) What is the order of distance of the nest star nearest to us than the sun?
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13) What is one par-sec?
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14) Explain the reason for expressing the distance between heavenly bodies in
terms of light years.
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6.5 ORGANISATION OF EARTH SYSTEM

Main Concepts

i) Earth is a unique planet.

ii) Our Earth is an active planet. Several phenomena are occurring within and on the
surface.of earth and in the atmosphere.
iii) The earth is organized into different layers by the process called differelitiatioli
(under influences of gravity).

iv) Relative position of continents is still changing.

 Teacl~ingLcarning of Teaching-Learning process
Concepts in Scicnce
The earth began as a cold aggregate of planetesimals (Small chunks of cosmic matter)
which consisted of silicon, iron and magnesium with traces of other elements. The
planetesimals collided with each other and stuck on. The kinetic energy produced by
collision got converted into heat. Beside, that Radioactive disintegration and gravitational
attraction further rose the temperature of the earth. The earth melted about 800 millions
years after its formation due to rise in temperature and began to reorganise itself under
the influence of gravity into different layers. This process is called differentiation. As a
result, three distinct layers were formed - the outer most CRUST, the underlying MANTLE
and innermost CORE. The following figure 6.4 depicts the different layers and their
characteristics

SINKING COOL
C1 iR1lENT

RISING
WARM
CURRENT

~ Fig. 6.4,

The crust and the mantle together contain all mineral deposits. The core is extremely hot
with a temperature of 4000°C and also very high pressure (3.7x107)Nm. Metals are
present in molten state in this layer. Due to the extreme heat in the core, convention
current arise in the mantle carrying heat from interior to the surface causing volcanic
eruptions and earthquakes.

The gases and water vapours which were trapped in the ~noleculesof primitive material
are liberated with the eruption of volcano to form the atmosphere and oceans during the
process of differentiation. The teacher can explain the evolution of life on earth by preparing
a chart showing its development on the earth. HeIShe must also explain of spheres of the
earth system i.e. the lithosphere, the atmosphere, the hydrosphere. Biosphere and their
important aspects such as interrelationships among the four spheres, and biogeochemical
cycles occurring in between the different spheres and the maintenance of balance and
also effects of disturbance in the inter-relationships of the four spheres.

The continents of the earth seem to be the scattered pieces of a single continent called
pangea. The following figures show the changing organization of the continents.

Methodology used: This sub-unit can be taught by field study-cum-enquiry method.

The differentiation of earth system is explained using the chart and transparencies. Field
trips to mines can also be arranged to make the lesson more interesf ng.

Teaching aid: Charts, transparencies and films.

 Universeand Space
Exploration

Pangaea
Fig. 6.5: Pangaea 200 million years ago.

180 million years ago: The original Pangaea landmass had split into two major continental
groups. The southern group, Gondwana-land, had itself started breaking up. India and
Antarctica. Australia becomes isolated. A rift had begun to appear between South
America and Africa and in the East, Africa was closing up the Tethys Sea

Fig. 6.6 (a) : 180 million years ago.

135 million years ago. Both Gondwana land and Laurasia continued to drift northwards
but the widening of the splits in the North Atlantic and Indian Oceans persisted. The
South Atlantic rift continues to lengthen and a further perpendicular rift appeared which
wi I1 eventually separate Greenland from North America. India continues heading northward
towards Asia.

Fig. 6.9 (b) : 135 million years ago.

65 million years ago. South America, completely separated from Africa, moved.quickly
to north and westwards. Madagascar broke free, But for Africa there is no sign of the
Red Sea rift which will split Africa from the Arabian Peninsula. The Mediterranean sea
is recognizable. In the south, Australia is still connected to Antarctica.
'leaching Learning of
Concepts in Scic~lcc

Fig. 6.6 (c) : 65 million years ago.

Present earth: India has moved northwards and is colliding with Asia, crumpling up the
sediments to form the folded mountain range of the Himalayas -South America has
rotated and moved west to connect with North America. Australia has also separated
from Antarctica.

Fig. 6.6 (d) : Prescnt earth.

Check Your Progress

Notes: a) Write your answers in the space given below.
b) Compare your answers with those given at the end of the unit.
15) Define pangea?
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16) Why tlie metal presents in core of earth are found in molten state?
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 Universe and Space
17) What are planetesimals? Exploration

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18) What is the process of differentiation?
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6.6 MINERALS AND COAL DEPOSITS

Main Concepts

i) Minerals, coal and oil are natural resources from which man prepare tools, machines
and commodities for his daily life.

ii) Minerals, oil and coal are the collection of useful materials buried under the upper
surface of the earth.
iii) Coal and oil were formed under pressure and temperature from the biomass.
Teaching-Learning Process
Most of the minerals are contained in the lithosphere are large reservoir of resources
useful to man. The minerals of the lithosphere provide the basic material from which Inan
prepares tools, machines and various other commodities for his daily life. The lithosphere
is also the repository of fuels-coal, oil and gas without which civilisation would not have
been possible. Look at the figure 6.7 showing the minerals deposit in the earth.

Fig. 6.7: Mineral deposits in the Earth.

Teaching Learning of Coal deposits are a major source of energy. We must make limited use of these resources
Concepts in Science because they are limited. We must think what would happen when these resources will
be finished? A balance is kept by nature between resources and environment. Resources
are concentrated deposits of some chemical compounds and minerals, which were created
by long acting processes that extract certain materials from the earth system and
concentrate it in a given region.
About 0.25 billion years ago, the earth was covered by dense forests. The biomass of the
forests were buried inside the earth by a fortunate sequence and converted into coal, oil
and gas. As a result, the CO, extracted from the atmosphere was not returned to the
atmosphere and thus green house effect was reduced.
~ e t h o d o l oused:
~ ~ Field study-cum-enquiry method and discussion method. The
differentiation of earth system is explained by charts and models. The models used in
geography can be used while teaching this unit. Use of films and transparencies will
make this unit more interesting.
Teaching aids: Charts, transparencies, films and field trips.

Check Your Progress

Notes: a) Write your answers in the space given below.
b) Compare your answers with those given at the end of the unit.
19) How is coal formed?
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20) How was petroleum formed?
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2 1) What are minerals? How were they deposited inside earth?
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6.7 SOLAR SYSTEM

Main Concepts

i) Solar system is a small component of Milky Way galaxy. It consists of nine planets,
asteroids, comets which revolve around the sun.

ii) Age of the solar system is 5000 billion years.

30
 Teaching-Learning Process U~~iversc
a11t1Space
Exploralion
It is assumed that about 5 million years ago our young sun was surrounded by a disc
shaped cloud of left over gases. These gases condensed to form small objects called
planetesimals which kept on constantly colliding with themselves and reassembling
themselves. Thus, planets were formed. During the formation of planets many large size
objects were hurled here and there. They were colliding with other object planners. The
craters on the surface of the Moon are the evidence of such collisions.
! There are 9 planets comprising Solar System alongwith satellites of planets, asteroids
!
and large number of comets and the detailed table is given below.
t
j
Table 6.1
MEMBER Distance Radius Mass Density Surface Period of Atmos- Satell~te
from 103Km (lines in gravity revolution phere
sw of I o3
( 106Km) Earths Kgm"
Mass)

SUN 696.00 332946 1.41 27.9 250 x 1 0 ' j H 2 H c 9 planets,

-
years comets,
Asteroids

MOON 150 1.74 0.0123 3.34 0.17 27.8 days I Vacuum 0

MERCURY 58 2.44 0.055 5.43 0.38 87 97 days Vacuum 0

VENUS 108 6.05 0.815 5.24 0.91 224.70 days CO, 0

EARTH 150 6 38 1.000 5.52 1.00 365 26 days N, 0 , , 80r,

19y, c o ,
CO,,H,,O, 1
MARS 228 3 39 0.107 3.94 0.38 686.48 days C0, 97%
N, 3% 2

JUPITER 778 71.40 317.8 4.33 2 54 11.89 years H,, HO,

CH,, NH, 16
SATURN 1431 60.00 95.16 0.70 1.08 29.46 years H,, HO, 24+
CH,, NH, Rings

URANUS 2886 25.40 14.50 1.3 0.91 84 years H,, HO 5+

CH,, Hc Rings

NEPTUNE 4529 24.30 17.20 1.76 1.19 164 years H,, HO,
- CH,,, He 2

PLUTO 5936 0.50 .0026 1.17 0.057 247.60 ? 1

years

You can discuss the properties of different members of Solar System with the help of the
I
above table.

Methodology used: This is Sub-unit can be taught by discussion/field study-cum enquiry

method. The lesson can is developed with the help of students. Skills of explanation will
also be very effective in this sub-unit.

Teaching aids: Static or dynamic model, Charts, Epidiascope, Overhead projector.

Teaching Learning of
Concepts in Science Check Your Progress
Notes: a) Write your answers in the space given below.
b) Compare your answers with those given at the end of the unit.
22) What is a planet?
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23) Which is the nearest planet from the earth ?
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24) Which planet has maximum number of satellites? -.

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25) Why does moon have craters?
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26) What are meteorites? Why are they visible?
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27) Which planet has maximum mass?
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 n

Universeand Space
28) Distinguish between meteor and meteorite? Exploration
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Main Concepts

i) Energy is generated in stars by the process of thermo-nuclear fusion.

ii) Two types of forces (strong and weak) play important role in evolution, life and
death of a star.
iii) Black holes attack all kinds of matter and radiations towards it.
iv) Stars are not permanent, they have a evolutionary process of birth and death, which
takes, thousands of years.
Teaching-Learning Process
Stars are self-luminousobjects. Energy is released in stars is a result of Thermo-nuclear
fusion. The energy in most of the stars, is either released by hydrogen getting converted
into Helium or in some stars energy by the fusion of Helium atom only. The total energy
radiated by a star is called its luminosity. The central temperature of stars varies from 10
to 30 million degrees. Teacher can explain the formation of star and its final stages
with the help of following diagrams using charts/transparencies/opaque projection.
The life history of a star can be depicted by the following flow charts:
1. Contraction, due to gravitational force of hydrogen and helium gas at about 173°C.

2. Temperature goes on rising to 107OC leads to formation of protostar.

3. Nuclear fusion occur 4,' H---3 4,He + Energy (heat + light).

5. After millions ofyears of nuclear hsion, the core shrinksdue to stoppages of reactions
and other shell expands forming the Red Giant Stage.

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Teaching Learning of '.
9
A star having mass equal to
+ +
A star 30-50 times A star 10 times the mass
Concepts in Science
or less than the sun loses the mass of sun of sun continues to
shell, and thecorecondenses u n d e r " e 0 e s contract further Fusion of
to form heavier nuclei with unc0n t r0I I ed carbon and helium lead to
large amount of light energy. contractioncausing a release of lot of energy
This is the white dwarf. very dense point causing the shell t o
3 He --) ':c + Energy. mass, which can explode- (Supernova)
even absorb 1 ight The core contracts further
completely, thus tofomave~denselum~
called black hole. called neutron star-

The stage are further exemplified by the following figures.

PROTOSTAR
Temperature inside the Core is - 263°C Temperature inside the Core is about 100°C
Fig. 6.8 (a) Fig. 6.8 (b)

.- - .oroduced
Force
due to Internal prcssurc
acting outwards

Gravitational force
@ shrinks

cOE

Outer acting inwards Outer shell

shell expands
Star Red Giant Star

Fig. 6.8 (c) Fig. 6.8 (d)

Outer shell

a-
Star
~ a v ~ mass
ng = Expanding White Dwarf
soiar mass outer shell Red
giant

Fig. 6.8 (e) : Formation of white dwarf Star.

Fig. 6.8 (g) : Formation of Black Hole.

Fig. 6.8 (f) : Formation of a supernova and neutron star.
Methodology used: This unit is very interesting and is taught by drawing different Universe and Space
diagrams as shown in figures above. Charts and projection can be used. The film show Exploration
will be the most effective tool in this unit.
- - -

Check Your Progress

Notes: a) Write your answers in the space given below.
b) Compare your answers with those given at the end of the unit.
29) What is neutron star?
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30) How is dwarf star formed?
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3 1) What is a black hole?
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32) What is supernova explosion?
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6.9 GALAXIES AND THEIR ORIGIN -- --

Main Concepts

i) Galaxy is a cluster of billion of stars, dust and gases.

ii) A galaxy is small of big cosmological explosion.

iii) There are billions of galaxies and all galaxies are not alike.
Teaching-Learning process
The stars are found in large bunches or clusters. Such cluster is called a GALAXY.
There are more than hundred billion (10") galaxies in our universe and each having more
than 10" stars. The galaxies are of different types.
Teaching Le;l rning of i) Normal Galaxy
Concepts in Science
ii) Radio Galaxy
Normal Galaxies emitsmall amount of radiations as compared to total amount of radiation
emitted in universe. Depending upon their shapes, the normal galaxies can be further
divided into three groups: -
a) Elliptcal Galaxies (IS%), b) spiral Galaxies (SO%), c) irregular Galaxies (2%)

Fig. 6.9 : Spiral galaxy. Fig. 6.10 : Irregular galaxy. Fig. 6.11: Elliptical galaxy.

Radio Galaxies: These galaxies emit million times more radiation than normal galaxies.
Milky Way: Our Galaxy is Milky Way (normal galaxy) which is a spiral galaxy. Its
length is 100, 000 light years. Its mass is 3 x lo4' Kg. The Milky Way rotates about its
center. It contains about lo1' stars. Which move in an orbit with its own speed. The
galaxy nearest to the Milky Way is Andromeda Galaxy.

SPIRAL ARM OF

10WM) LIGHT YEARS

C = Galactic Centre,
. S = Represents the position of the Sun

Fig. 6.12. Milky way: Transverse view. Fig. 6.13: Milky way: Aerial view.

The distribution of galaxies in the universe is not uniform. All the galaxies are moving
away from one another with a speed that increases as the distance between them increases.
The fact is supported by the Doppler's Red Shift of the galaxies.
Methodology used: i) Explanation method
ii) Group discussions
This unit can taught by explanation method and lesson can developed with the help of
students. The film show if possible can be arranged.
Teaching aids: Charts, transparencies, opaque projection, and films.
Check Your Progress
Notes: a) Write your answers in the space given below.
b) Compare your answers with those given at the end of the unit.
34) Whatis a Galaxy?
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 Universe and Space
35) Differentiate between radio & normal galaxy? Exploration

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36) Explail~structure of Milky Way.

6.10 SATELLITE AND SPACE EXPLORATION

Main Concepts

i) Space exploration is very important in providing important information about the

origin of the Universe.
ii) Artificial satellites help man in communicatio~~,
weather forecasting in the field of
meteorology, geographic and geological survey of earth.
iii) Inter-planetary vellicles have widened the knowledge of solar system and outer
space.
Teaching-Learning Process
Artificial satellites are playing very importal~trole in space exploration by helping in,
weather monitoring, weather forecasting, in making long distance communications, in
field of meteorology, geographic and geological survey of earth. All these aims of space
exploration must be discussed student - teacher may refer to Science Reporter,
newspapers, magazines and gather information about the space exploration.
Voyager 2, is an example one of the most sophisticated and successful space probe ever
Iaunclled by mankind. It gave information about Jupiter, Saturn, Uranus and Neptune.
Fig. 6.14, illustrates the pat11 followed by Voyager. Other, efforts in terms of space
explorations are given in table 6.2. and table 6.3.

JUPITER

Fie. 6.14 37
Teaching Learning of Table 6.2
Concepts in Science
Name of space mission I Date of its Remarks
associated country
1. Sputnik -I (USSR, now Russia)
I launching
Oct. 4, 1957 First ever artificial satellite
launched in space.

First satellite to carry a

2. Sputnik-11 (USSR, now Russia) Nov. 3,1957 living dog into space.

3. Score (USSR, now Russia) Dec. 18,1958 First communication

satellite put into space.
First space probe, which
4. Lurze-3 (USSR, now Russia) Oct. 4, 1961 sent photographs of the far
side (not visible from the
earth) of the moon.

5. Vostok-I (USSR, now Russia) April 12, 1961 First space flight by a man
(Yuri Gagarin).

6. Mercury -4 (USSR) May 4, 1961 Second space flight by man

(Alan Shepherd)

7. Vostok-II Dec. 4, 1963 First space flight by a women

(Volentena Tereshkova).
First man to walk in space
8. Vostok-III (USSR, now Russia) Oct. 1964
(Alexei Leonov). He spent
10 minutes outside the
spacecraft

9. INTELSAT-I (USSR, now Russia April 6, 1965 First communication

satellite for commercial
use.
Nov. 16, 1965 First spacecraft to land on
Venus.

11. Surveyor-I (USA) June 2,1966

12. Surveyou - V Sept. 1967
13. Luna-9 Oct. 21,1968 First successful landing by
a spacecraft on the moon's
surface.

14. Soyuz -4 (USSR, now Russia) I Jan. 14,1969 First experimental space

15. Apollo-II (USA) July 16, 1969 Neil Amstrong becamexthe

first human-being to set
foot on the moon. Edwin
Aldrin followed after 8
minutes.

16. Lunu-26 (USA) Dec. 1992

17. Mars-2 (USA) May 19,1971 First landing of a space

probe on Mars (planet),
 Universe and Space
1 8. Pioneer-10 (USA) March 2, 1972 First hpace probe to explore
Exploration
the asteroid belt, and to
take Photographs of
Jupiter from the close range.
19. Landsat (USA) July, 1972 First satellite for'remote
sensing.
20. Apollo-Soyuz (USA+USSR) July 15, 1975 First it~ternatiouallinkup of
two satellites in space (test
project.)
2 1 . INTELSA T-II 1966 Communication satellite
22. INTELSA T-III 1968 Communication satellite
23. INTELSAT-IV 1971 Communication satel I ite
24. INTELSAT- V 1981-83 (:ommunication satellite
a 25. INTELSAT-VI 1986 Communication satellite

Table 6.3
SL No. Name of satellite Date of Name of the country
launching which launched it

2. APPLE June 19,1989 ARIANE Success

-
3.
, Rohini May 31,1989 lndia Failure
4. Bhaskar-2 Nov. 20,1982 USSR (now Russia) Success
5. INSAT-IA Sept. 4, 1982 USA Failure
6. INSAT-IB Aug. 30 1983 USA Success
7. SROSS-I March 24,1987 India Failure
8. INSAT-1C July 12,1988 USA Failure
9. SROSS-2 July 13,1988 India (ASLV) Failure
10. INSAT-ID June 12, 1990 IJ SA Success
11. 1RSlB Aug. 29,199 1 USSR (now Russia) Success
12. SROSS-3 May 19,1992 India (ASLV) Success
13. INSAT-2A July 10, 1992 ARl ANE (European Success
launched vehicle)
14. INSAT-2B July 23, 1993 ARl ANE Success
15. IRS- I E Sept.20, 1993 PSLV D1 Failure
16. SCROSS-C;! May 10,1994 India (ASLV-D4) Success
17. IRSP;! Oct. 1 5,1994 PSLV D2 Success
18. INSAT-2C Dec. 7,1995 lndia by the European Success
(Life 7 years) launch vehicle ARlANE
Methodology used: The teacher can discuss history of space exploration and space
research in India to make the lesson more interesting. By using the data in Tables 6.2
and 6.3.
Geostationary Artificial Satellites can be used for spying, form thc outer space. These
can be used to know events related to military purposes. The satellite can be useful to
find the exact location of a distressed conditional ship in the sea.
Teaching aids: i) Charts. static or working models transparencies, film on satellites. 39
Teaching Learning of Check Your Progress
Concepts in Science
Notes: a) Write your answers in the space given below.
b) Compare your answers with those given at the end of the unit.
37) What is a Satellite?
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
38) What is a geostationary satellite?
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
39) What does INSAT stand for?
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
40) What are various functions performed by a Geostationary satellite?
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................

6.11 LET US SUM UP

The universe contains everything from finest fundamental particles, to big structures
such as planets, stars, super stars and galaxies. Even with the latest development in
astronomy using Hubble's space telescope and radio astronomy, the true picture is far
from clear. The cosmologists do not know how old or how big is our Universe. Nor is it
possible to assert as to what most of it is made up of. The latest studies, however, have
revealed that we can say with some confidence that:
- The Universes started out in a very hot and dense state.
- It originated between 8-25 billion years ago;
- It has been expanding onwards ever since.
- Galaxies are cluster of stars and have a definite pattern.
- A planet is orbiting the star 47 Ursac Majoric (34 light years from the earth) which
has a mass 2.5 times of Jupiter.
- Amongst the planets, our planet Earth is the only living planet. Space probes Universe and Space
have helped man to understand the outer space to a better and greater extent. Exploration
- Two more planets, which are outside the Milky Way have been recently detected.

6.12 UNIT-END EXERCISES

Discuss the cosmologicattheories of the universe.
How will you estimate the mass of 'Milky way'?
Discuss importance of minerals in the development of India.
Name the constituents of the solar system and discuss their characteristics.
Give life history of stars.
Explain how energy is liberated in stars.
Explain structure of our Galaxy.
Discuss the aims of space exploration.
Give a brief history of space exploration in India.
Give a brief account of voyager space probes. What information have been given to
us about the outer planets?
1 1. Explain the purpose of PLSV and ASLV.
12. Discuss application of space science in satellite communication.
13. Mention factors which made earth to lead in biological revolution.
14. Define the terms; Magma, Volcanic eruption, Earthquake, Lithosphere and Ozone
layer.

6.13 ANSWERS TO CHECK YOUR PROGRESS

1. Universe is the total of all the matter, energy, and space that man is capable of
experiencing. The uqiverse is currently best described in terms of a four-dimensional
curved spaceline cqSltinuum.
2. 8 -25 billion years.
3. Stars have their own source of light and energy. They appear fix with respect to
neighboring stars. Planets are visible by light reflected by them and appear wandering
in space.
4. Cluster of stars, gases, matter and energy forms a galaxy.
5. lOl0 or even more.
6. 101° x lo4'kg.
7. 9.45 x lOI5Km.
8. 8 to 25 billion years.
9. Quasi stellar radio sources. These are outermost objects ofthe universe. Velocity of
their recession is 90% ofvelocity of light.
10. 100,000 light years.
Teaching Learning of 11.
Cot~ceptsin Science
12. 4.3 light years.
3.20 light years or 3.08 x 1016~n.
Since the order of distance is very high.
The heating up the earth's atmosphere due to the trapping of infra red rays by
carbon dioxide layer in the atmosphere is called green house effect.
A layer of Ozone around the earth surface is at a height of 30 Km. It is responsible
for absorbing a large proportion ofthe Sun's ultra violet radiations.
Initial stage ofplanets -Cold gas and dust in condensed form in the shape ofchunks
are called planetesimals.
The reorganization of earth due to gravitational attraction.
Coal was formed by the process of carbonization when biomass of buried planets
changedinto coal at high temperature and pressure in absence of air.
Petroleum was also formed by the process of carbonization with biomass of animals.
Minerals are useful material stored inside the earth. The biomass of the forests
(0.25 billion years ago) and some useful material were buried under the earth and
concerted into minerals.
Heavenly body revolving in definite orbit about the Sun.
Mercury
Jupiter
Because of constant hitting of the terrestrial object on the surface of earth.
They are rocky material. When they enter into earth atmosphere heat is produced
due to friction with atmosphere and light is emitted out by meteorites.
Jupiter
Meteorites are able to reach the surface of earth while meteors after the death of
star where mass is more than 1.4 times solar mass.
They are also called Pulsar. They consist of neutrons. Neutron stars are formed
after the death of star where mass is more than 1.4 times solar surface.
It is a heavy nuclei with large amount of light energy formed after condernsation of
a star having mass 1.4 times more than the sun.
It is a dense nuclei, which can absorb light.
Explosion of star shell due to carbon helium fusion.
Clusters of stars.
Light coming from normal galaxy is more than radio galaxy.
Refer to Sec. 8.9.
A body that rotates in orbit around other body of greater mass.
A satellite which appears stationary with respect to earth. Its time period of rotation
is 24 hours.
Indian National Satellite.
39. Weather monitoring, Weather forecasting spying the event related to war, making Universe and Space
long distance call. Exploration

40. A belt of charged particles trapped within earth's magnetic field. i) from 2400 km
to 5600km, ii) from 1300 km to 1900km.

6.14 SUGGESTED READINGS

Science Reporters.

NCERT: Teaching of Science in Secondary Schools.

NCERT: Science of Xth Class
NCERT: Physics For Class XI & XII.
Fundamental Physics, Pradeep Publications.
Sehgal & Chopra : Senior School Physics.
Ensic Principle of Physics, Pitambar Publishing Company.
Physics, Arya Book Depot.