1. The document discusses the celestial bodies that can be seen in the night sky, including stars, planets, and other astronomical objects that orbit the Sun. 2. It explains that stars produce their own light and heat, while planets like Earth receive light from stars and have no internal light source of their own. 3. The Solar System is made up of the Sun and objects that orbit it, including 8 planets, their natural satellites like Earth's Moon, asteroids, and comets.

3. Chapter – 1
The Earth In The Solar System
BY
Mr. BHAURAO GUNJAL (M.A.M.ED.)
TGT (GEOGRAPHY), EMRS, PETH ROAD, NASHIK

4.  How wonderful it is to watch the sky after sunset! One would first notice
one or two bright dots shining in the sky. Soon you would see the number
increasing. You cannot count them any more. The whole sky is filled with
tiny shining objects – some are bright, others dim. It seems as if the sky is
studded with diamonds. They all appear to be twinkling. But if you look
a5t them carefully you will notice that some of them do not twinkle as
others do. They glow without any flicker just as the moon.
 Along with these bright objects, you may also see the moon on most of the
days. It may, however , appear at different times, in different shapes and at
different positions. You can see the full moon only once in about a
month’s time, it is Full Moon night or Poornima. A fortnight later, you
cannot see it at all. It is a New Moon night or Amavasya. On this day ,
you can watch the night sky best, provided it is a clear night. So lets see…
Full Moon New Moon

5.  By definition a celestial body is any natural body outside of the Earth's
atmosphere. Easy examples are the Moon, Sun, and the other planets of
our solar system. But those are very limited examples. The Kuiper belt
contains many celestial bodies. Any asteroid in space is a celestial body.
 The sun, the moon all and those objects shining in the night sky are called
Celestial Bodies.

6.  Some celestial bodies are very big and hot. They are made up of gases.
They have their own heat and light, which they emit in large amounts.
These celestial bodies are called stars. The sun is a star.
 You know there is one the poem “Twinkle, twinkle, little star, how I
wonder what you are. If we look up at the sky at night, we see millions of
tiny diamond-like stars.“ like this stars are twinkling objects appear in the
night sky. Except sun other stars are very far from us that’s why, we do not
feel their heat or light. And they looks very small in the sky.

7.  While watching the night sky, you may notice various patterns formed by
different groups of stars. These are called Constellations.
 Urasa Major or Big Bear is one such constellation. One of the most easily
recognisable constellation is the small bear or Saptarishi (Sapta-seven,
rishi-sages). It is a group of seven stars that forms a part of the large Urasa
Major Constellation.

8.  In ancient times, people used to determine directions during the night with
the help of stars. The North Star indicates the north direction.it is called
the Pole Star.
 It always remains in the same position in the sky. We can locate the
position of the Pole Star with the help of the Saptarishi. Look at following
figure-
 The pole star or Polaris is directly above the north pole of the earth and
stays there all of the time. All other stars appear to move slowly from east
to west as the earth rotates, but the pole star stays stopped at due north.

9.  Some celestial bodies do not have their own heat and light. They are lit by
the light of the stars. Such bodies are called Planets.
 The word ‘planet’ comes from the Greek word “Planetai” which means
‘wanderers’.
 The Earth on which we live is a planet. Ti gets all its heat & light from the
sun, which is our nearest star.
 If we look at the earth from a great distance, say the moon, it will appear to
be shining just as the moon.
Planets
Inner Planets Outer Planets
(Terrestrial small & rocky) (Gas Giant, Large & low density)
1. Mercury 1. Jupiter (gas)
2. Venus 2. Saturn (gas)
3. Earth 3. Uranus (ice)
4. Mars 4. Neptune (ice) 5. Pluto (dwarf planet)

10.  Ceres:- Largest object in asteroid between Mars & Jupiter
 Pluto:- Small size, offbeat orbit, beyond Kuiper Belt, now Planetoid
 Eris:- 2003 UB313- 10th planet & largest dwarf discovered newly
 Oort Cloud:- Are composed of ices like ammonia, methane & water
 Kuiper Belt:- Ice belt beyond Neptune, between Neptune & Pluto
 Asteroid Belt:- Belt between Mars & Jupiter

11.  They are made up mostly of rock and metal.
 They are very heavy.
 They move slowly in space.
 They have no rings and few moons (if any).
 They have a diameter of less than 13,000 km.
 i.e Mercury, Venus, Earth, Mars, and Pluto
Characteristics of Gas Giants Planets
 They are made up mostly of gases (primarily hydrogen & helium).
 They are very light for their size.
 They move quickly in space.
 They have rings and many moons.
 They have a diameter of less than 48,000 km
 i.e Jupiter, Saturn, Uranus, and Neptune

12.  The sun, Eight planets. Satellites & some other celestial bodies known as
asteroids & meteoroids comets, interplanetary gas, dust, and all the
“space” in between them form the Solar System.
 ‘Sol’ in Roman mythology is the “Sungod”. ‘Solar’ means ‘related to the
sun. the family of the sun is therefore called Solar System. We often call it
a solar system with the sun as its Head.
 The solar system is entirely dependent on sun & the only one which is
self-luminous i.e which has its own light & heat. Rest of the planets reflect
the light received from sun. ‘Stars produce light, Planets reflect light’.
 There are eight planets in our solar system. In order of their distance from
the sun, they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus,
Neptune.
 They can easy memorise in order of their distance from the sun are as -
‘My Very Efficient Mother Just Served Us Nuts’.
The nine planets of the Solar System are named for Greek and Roman
Gods and Goddesses.

13.  All the eight planets of the solar system move around the sun in fixed
path. These paths are elongated. They are called Orbits.

15.  1. The sun is in the centre of the solar system. It is huge
& made up of extremely hot gases. It provides the
pulling force that binds the solar system.
 2. The sun is the ultimate source of heat & light for the
solar system. But that tremendous heat is not felt so
much by us because despite being our nearest star. It
is far away from us, the sun is about 150 million km
away from the earth.
3. The light from the sun takes approximately 8 minutes to reach the earth.
4. It is the source of energy for life on earth.
5. On the sun’s surface, there are dark patches known as sunspots.

16.  Mercury has a revolution period of 88 days & rotation of 59 days.
Mercury has extreme temperature fluctuations, ranging from 800F (day
time) to -270F (nigh ttime).
 Even though it is the closest planet to the sun, Scientists believe there is
ICE on Mercury! The ice is protected from the sun’s heat by crater
shadows.
 It does not have any satellite. There is no seasons on its surface.

17.  Venus is the brightest & hottest object in the sky after the sun and moon
because its atmosphere reflects sunlight so well. People often mistake it
for a star.
 Its maximum surface temperature may reach 900F.
 Venus has no moons and takes 255 days to complete an orbit & takes 243
days to complete one spin on axis.
 It is also known as ‘sister ‘ or ‘twin’ planet to earth because of its similar
size & mass to earth.

18.  Earth is also known as ‘Watery’ planet because 71% of its surface is
covered by water.
 It reflects about one thirds of sunlight it receives. The earth’s atmosphere
scatters the light & creates a blue effect, so it is called “Blue planet”.
 The earth is the third nearest planet to the sun. in size, it is the fifth largest
planet. It is slightly flattened at the poles. That is why, its shape is
described as a Geoid means an earth-like shape.
 Conditions favourable to support life are probably found only on the earth.
It has water & air, which are very essential for survival. The air has life
supporting gases like oxygen. The earth is a unique planet in the solar
system.
 It takes 265 days to complete an orbit & take 1 days to complete one spin
on axis. Moon is the only satellite of the earth.

19.  Our earth has only one satellite, that is the Moon. It’s diameter of only ¼
of the earth. It looks bigger to us as it is very close to us. It is about
3,84,400 km away from us.
 The moon moves around the earth in about 27 days. It takes exactly the
same time to complete one spin. As a result, only one side visible to us.
 The moon’s surface is covered in dust and rocky debris from meteor
impacts. It has no water or atmosphere.
 The moon reflects light from the sun onto the earth’s surface.
 The moon is the only satellite other than earth on which humans set foot.
Neil Armstrong was the first man to set on the surface of the moon on 29
July 1969.

20. 1. Like Earth, Mars has ice caps at its poles.
2. Mars has the largest volcano in our solar system:
Olympus Mons is approximately 15 miles high.
3. Mars appears red because of iron oxide, or rust, in its soil.
4. Mars has two moons and takes about two years to
complete an orbit.
Jupiter (The Giant Planet)
1. Jupiter is the largest and most massive planet.
2. It’s diameter is 11 times bigger than that of the Earth’s.
3. It takes about 12 years for Jupiter to orbit the sun.
4. Jupiter has 16 known moons.

22. 1. . 1. Saturn is composed almost entirely of hydrogen and helium.
2. Saturn has many rings made of ice. Saturn’s rings are very
wide. They extend outward to about 260,000 miles from
the surface but are less than 1 mile thick.
3. Saturn has 18 known moons, some of which orbit inside the
rings!
4. It takes Saturn about 30 years to orbit the sun.
Neptune
1. Neptune has the fastest winds in the solar system: up to
2,000 km/hr.
2. Neptune is also blue in color due to methane gas in its
atmosphere.
3. Neptune takes 165 years to orbit the sun and has 8 moons.

23.  Pluto has only one moon and takes about 249 years to orbit the sun.
 Part of Pluto’s orbit passes inside that of Neptune, so at times Neptune is
the planet farthest from the sun.
 Pluto was located and named in 1930 as the ninth planet, but today Pluto
is no longer considered a planet.

24.  Asteroids:- Apart from the stars, planets & satellites, there are numerous
tiny bodies which also move around the sun. these bodies are called
asteroids. They are found between the orbits of Mars & Jupiter. That’s are
the part of planet which exploded many years back.
 Meteoroids:- The small pieces of rocks which move around the sun are
called Meteoroids. Sometimes these meteoroids come near the earth &
tend to drop upon it. They get heated up & burn, it causes a flash of light.

25.  We see a whitish broad band, like a white glowing path across the sky on a
clear starry night. It is a cluster of millions of stars. This band is the Milky
Way Galaxy. Our solar system is a part of this galaxy. In ancient India, it
was imagined to be a river of light flowing in the sky. Thus , it was named
Akash Ganga. A galaxy is a huge system of billions of stars, & clouds of
dust & gases. There are millions of such galaxies that make the Universe.
It is difficult to imagine how big the Universe is. Scientists are still trying
to find out more & more about it.

26.  1. A group of _________ forming various patterns is called a
____________.
 2. A huge system of stars is called __________.
 3. _________ is the third nearest planet to the sun.
 4. Planets do not have their own ________ & _________.
 5. The Pole Star indicates the direction to the _________.
 6. Define Celestial bodies.
 7. Define Constellations.
 8. The natural satellite of the earth is -- (Sun, Mercury, Moon, Pole Star)
 9. The planet known as the “earth’s Twin” is – (Jupiter, Venus, Saturn,
Mercury)
 10. What is meant by the ‘solar system’?