The document discusses various topics related to stars and the solar system. It describes the moon's phases and surface features. It explains that stars are spheres of plasma held together by gravity, with the closest star being the sun. The solar system contains planets, asteroids, comets, and meteors that revolve around the sun due to its gravitational pull. Artificial satellites also orbit Earth and are used for applications like weather forecasting, telecommunications, and remote sensing.

1. STARS AND THE
SOLAR SYSTEM

2. MOON
 The day on which the whole disc of the moon is
visible is known as the Full moon day.
 Every night the size of the bright part of the moon
appears to become thinner and thinner.
 On the 15th day the moon is not visible, this day is
known as the New moon day.
 The next day, only the small portion of the moon
appears in the sky, this is known as the Crescent
moon.
 Again the moon grows larger everyday. On the 15th
day once again we see a full view of the moon.

3. PHASES OF MOON
 The various shapes of the bright part of the moon as
seen during a month are called phases of the
moon.
 The time period between one full moon to the next
full moon is slightly longer than 29 days.
In many calendars this period is called a month.

4. THE MOON’S SURFACE
 The Moon’s surface is dusty and barren. There are
many craters of different sizes. It also has a large
number of steep and high mountains. Some of these
are high as the highest mountains on the Earth. The
moon has no atmosphere. It has no water.
 On 21st July, 1969 the American astronaut, Neil
Armstrong, landed on the moon for 1st time.

5. STARS
 A Star is a luminous sphere of plasma held together
by its own gravity. The nearest star to Earth is the
Sun. Many other stars are visible to the simple eye
from Earth during the night, appearing as a immense
distance from Earth. multitude of fixed luminous
points in the sky due to their immense distance from
Earth.

6. LIGHT YEAR
 The Sun is nearly 150000000 km away from the
Earth.
 The next nearest star is Alpha Centauri. It is at a distance
of about 40000000000000 km from the Earth.
 Large distances are expressed in a unit known as Light
year. It is a distance travelled by light in a year. The
speed of light is 299792 km per second. Thus the
distance of the Sun from the Earth may be about 8 light
minutes.
 The distance of Alpha Centauri is about 4.3 light years.

7. POLE STAR
 A Pole star is a visible star, preferably a prominent
one, that is approximately aligned with the Earth's
axis of rotation; that is, a star whose apparent
position is close to one of the celestial poles, and
which lies approximately directly overhead when
viewed from the Earth's North Pole or South Pole.

8. CONSTELLATIONS
 The stars forming a group that has a recognisable
shape is called a Constellation.
 The shapes of constellations resemble objects familiar
to ancient people.
 We can see Ursa Major during the summer time in
the early part of the night. It is also known as the Big
Dipper, the Great Bear or the Saptarshi.

9. ORION
 Orion is well known constellation that can be seen
during winter in late evenings. It is one of the most
magnificent constellations in the sky. It also has
seven or eight bright stars. It is also called the
Hunter. The 3 middle stars represent the belt of the
hunter. The four bright stars appear to be arranged in
the form of a quadrilateral.

10. SIRIUS
 The star Sirius which is the brightest star in the sky
is located near Orion.
 To locate Sirius imagine a straight line passing
through the middle stars of Orion.

11. SOLAR SYSTEM
 The sun and the celestial bodies which revolve
around it form the Solar system.
 It consists of large number of bodies such as planets,
comets, asteroids and meteors.
 The gravitational attraction between the sun and
these objects keep them revolving around it.
 The Earth, also revolves around the Sun. There are
seven other planets that revolve around the Sun.
 The eight planets in there order of distance from the
Sun are:- Mercury, Venus, Earth, Mars, Jupiter,
Saturn, Uranus and, Neptune.

13. SUN
 The Sun is by far the largest object in the solar
system. It contains more than 99.8% of the total mass
of the Solar System. It is often said that the Sun is an
"ordinary" star.
 It continuously emits huge amounts of heat and light.
It is the source of almost all energy on the Earth. It is
the main source of heat and light for all planets.

14. PLANETS
 The planets look like stars, but they don’t light of their
own. They merely reflect the sunlight that falls on them.
 A planet has a definite path in which it revolves around
the Sun. This path is called an Orbit.
 The time taken by a planet to complete one revolution is
called its period of revolution. The period of revolution
increases as the distance of the planet increases from
the Sun.
 Besides revolving around the sun, a planet also rotates
on its own axis like a top. The time taken by a planet to
complete one rotation is called its period of rotation.

15. MERCURY
The planet Mercury is nearest to the sun. It is the
smallest planet of our solar system. Because mercury
is very close to the Sun, it is very difficult to observe it,
as most of the time it is hidden in the glare of the Sun.
However, it can be observed just before Sun rise or
just after Sunset, near the horizon. So it is visible only
at places where trees or buildings do not obstruct the
view of the horizon. Mercury has no satellite of its
own.

16. VENUS
 Venus is earth’s nearest planetary neighbour. It is
the brightest planet in the night sky.
 Sometimes Venus appears in the eastern sky
before Sunrise. Sometimes it appears in the
western sky just after Sunset. Therefore it is often
called a morning or an evening star, although it is
not a star.
 Venus has no moon or satellite of its own. Rotation
of Venus on its axis is somewhat unusual. It rotates
from East to West.

17. EARTH
 The Earth is only the planet in the solar system on
which life is known to exist. Some special
environmental conditions are responsible for the
existence and continuation of life on the Earth.
These include just the right distance from the sun,
so that it has the right temperature range, the
presence of water and suitable atmosphere and a
blanket of ozone.
 The axis of rotation of the Earth is not perpendicular
to the plane of its orbit. The tilt is responsible for the
change of seasons on the Earth.

18. EQUATOR OF THE EARTH
 The plane of the equator is called the equatorial
plane. The plane in which the earth revolves around
the Sun is called the orbital plane of the earth. These
two planes are inclined to each other at an angle of
23.5 degree. This means that the axis of the earth is
inclined to its orbital plane at an angle of 66.5
degree.

19. MARS
 Mars is the 4th planet from the sun and the 2nd
smallest planet in the solar sytem.
 The next planet, the first outside the orbit of the Earth
is Mars. It appears slightly reddish and therefore, it is
also called the Red planet.
 Mars has two small natural satellites.
 It is named after the Roman god of the war.

20. JUPITER
 Jupiter is the largest planet of the solar system. It is
so large that about 1300 earths can be planets inside
the giant planet. However, the mass of Jupiter is
about 318 times that of our Earth. It rotates very
rapidly on its axis.
 Jupiter has a large number of satellites. It also has
faint rings around it.

21. SATURN
 Beyond Jupiter is Saturn which appears
yellowish in colour. Its density is less than that of
water.
 Saturn also has a large number of satellites.
 Saturn has a prominent ring that consists of nine
continuous main rings and three discontinuous
arcs and that is composed mostly of ice particles
with a smaller amount of rocky debris and dust.

22. URANUS AND NEPTUNE
 These are the outermost planets of the solar system.
Uranus also rotates from east to west. Uranus is
highly tilted rotational axis. In its orbital motion it
appears to roll on its side.

23. ASTEROIDS
 There is a large gap between the orbits of Mars and
Jupiter. This gap is occupied by a large number of
small objects that revolve around the sun. These
are called as asteroids. Asteroids can only be seen
through last telescopes.

24. COMETS
Comets are members of solar system. Revolve
around the sun in highly elliptical orbits. However
their period of revolution around the sun is usually
very long. A Comet appears generally as a bride
had with a long tail. The length of the tail grows in
size as it approach to the sun. The tail of a Comet is
always directed away from the Sun. Many comets
are known to appear periodically.

25. METEORS
At night, when the sky is clear and the moon is not
there, you may sometimes a bright streaks of light in
the sky. These are commonly known as shooting
stars, all though they are not stars. They are called
meteors. A meteor is usually a small object that
occasionally enters the earth’s atmosphere. At that
time it has a very high speed. The friction due to the
atmosphere heated up close and evaporates quickly.
That is why the bright steak last forever short time.

26. METEORITES
Some meteor are large and so they can reach the
earth before the evaporate completely. The body
that reaches the earth is called a meteorite.
Meteorites help scientist in investigating the nature
of the material from which the solar system was
formed.

27. METEOR SHOWERS
When the Earth crosses the tale of a comet,
swarms of meteors are seen. These are known as
meteor showers. Some Meteor shower occur at
regular interval each year.

28. ARTIFICIAL SATELLITES
There are number of artificial satellites which are orbiting
the earth. Artificial satellites are different from natural
satellites. Artificial satellites are man made. They are
launched from the Earth, revolve around the earth much
closer than earth natural satellite, the moon. India has built
and launch several artificial satellites. Aryabhatta was the
first Indian satellite. Some other Indian satellites are INSAT,
IRS, Kalpana-1 EDUSAT, etc. Artificial satellites have many
Pratik practical applications they are used for forecasting
weather translating television and radio signal they are you
also used for telecommunication and Remote Sensing.

29. THANKS FOR
WATCHING
MADE BY:- Ayush Singh