The Universe is everything that exists- Stars , Planets , Moons , other Heavenly bodies , everything that exists on these heavenly bodies , such as animals and

plants on the earth, and the vast empty space in between. It is even impossible to

even imagine its size . The estimated diameter of the observable universe is

about 93 billion Light Years. Our earth is not alone in the universe there are 8 more

Planets along .

THE UNIVERSE

OUR PLANETS & STARSStars are huge spinning balls of hot luminous gases. All stars give out their own light . Most stars are made up of entirely of two gases –

Hydrogen & Helium. In the center of the stars , hydrogen atoms combine to form

helium atoms, during this huge amount of energy is released in the form of heat & light .

Planets are heavenly bodies that revolve around the sun. They do not have light of their own & reflects the light of sun to us.

They are smaller than stars .

SUN ( star )- The Sun is the star at the center of the Solar System. It is almost

spherical and consists of hot plasma interwoven with magnetic fields. It has a diameter of about 1,392,684 km, around

109 times that of Earth, and its mass 1.989×1030 kilograms, approximately

330,000 times the mass of Earth . Chemically, about three quarters of the

Sun's mass consists of hydrogen, whereas the rest is mostly helium. It is the closest star to the earth. It is the source of almost all energy on the earth as well as on other

planets.

MERCURY- Mercury is the smallest and closest to the Sun of the eight planets in the Solar System with an orbital period of about 88 Earth days. Seen from Earth, it

appears to move around its orbit in about 116 days, which is much faster than any

other planet. It has no known natural satellites . As it has almost no atmosphere

to retain heat, Mercury's surface experiences the greatest temperature

variation of all the planets, ranging from −173 °C; −280 °F at night to 427 °C; 800

° during the day at some equatorial regions.

VENUS - Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has no natural satellite.

After the Moon, it is the brightest natural object in the night sky,

reaching an apparent magnitude of −4.6, bright enough to cast shadows.

As Venus is an inferior planet from Earth, it never appears to venture far from the Sun: its elongation reaches a

maximum of 47.8°.

EARTH- Earth, also known as the World is the third planet from the Sun, the

densest planet in the Solar System, the largest of the Solar System's four

terrestrial planets, and the only celestial body known to accommodate life. The Earth's biodiversity has evolved over hundreds of million years, expanding

continually except when punctuated by mass extinctions. It is home to over

eight million species. There are over 7.2 billion humans who depend upon its

biosphere and minerals.

MARS- Mars is the fourth planet from the Sun and the second smallest planet in the Solar System, after

Mercury, It is often described as the "Red Planet" because the iron oxide prevalent on its surface gives it a

reddish appearance. Mars is a terrestrial planet with a thin

atmosphere, having surface features reminiscent both of the impact craters

of the Moon and the volcanoes, valleys, deserts, and polar ice caps of

Earth.

JUPITER- Jupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a gas giant with mass one-thousandth of that of the Sun but is two

and a half times the mass of all the other planets in the Solar System combined.

Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, although helium only comprises about a tenth of the number of molecules. It may

also have a rocky core of heavier elements, but like the other gas giants,

Jupiter lacks a well-defined solid surface.

SATRUN- Saturn is the sixth planet from the Sun and the second largest

planet in the Solar System, after Jupiter. Saturn is a gas giant with an average radius about nine times that of Earth. Saturn's interior is probably composed of a core of iron, nickel and rock (silicon and oxygen compounds),

surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium and an outer gaseous layer.

URANUS- Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Uranus is similar in composition to Neptune, and both are of different

chemical composition to the larger gas giants Jupiter and Saturn. Uranus's

atmosphere, although similar to Jupiter's and Saturn's in its primary composition of

hydrogen and helium, contains more "ices", such as water, ammonia, and methane, along with traces of other

hydrocarbons.

NEPTUNE- Neptune is the eighth and farthest planet from the Sun in the

Solar System. It is the fourth-largest planet by diameter and the third-

largest by mass. Among the gaseous planets in the Solar System, Neptune

is the most dense. Neptune is 17 times the mass of Earth and is slightly more

massive than its near-twin Uranus, which is 15 times the mass of Earth but not as dense. Neptune orbits the Sun at an average distance of 30.1

astronomical units.

CONSTELLATIONS

Thousands of year ago , astronomers divided the stars into groups, and drew

imaginary pictures around them , such as that of a hunter or a bear. This made it easier for them to remember the stars

patterns. Such a group of stars is called a constellation. Toady, 88 constellations are recognized by astronomers. Some Of the

constellations are given one the next slide …

THE MOONA Celestial object that revolves around a planet is known as a Natural satellite or Moon of the planet. Most planets have moons revolving

around them.

The Earth has only one moon . It is held in orbit around the Earth’s gravity. It shines because it reflects the light of the sun. It is dry and barren with no atmosphere. Its surface is covered with

several mountains and craters. It has a diameter of about One-Fourth that of earth and

its mass is about one-hundredth that of the earth. Its distance from the earth is 3,84,400

Kilometers.

The moon completes its one revolution around the earth in 27.3 days . It also

rotates once on its axis in the same period of time.

ARTIFICIAL SATELLITES

An artificial satellite is an artificial object which has been intentionally placed into orbit, which revolve around planets. The

first satellite was sent by USSR on 4 October 1957. It was called Sputnik-I .

Satellites are used for a large number of purposes. Common types include military and civilian Earth observation satellites, communications satellites, navigation

satellites, weather satellites, and research satellites etc.

WHAT IS THE BIG BANG THEORY ?

Astronomers found that the universe was expanding. So, they put forward a theory to explain how the universe originated. They believe that about 15 billion years ago all thee matter in the universe was gathered

into a single mass. Suddenly the mass exploded , sending particles flying in all directions. These particles formed the

galaxies with the stars and planets. These galaxies are still flying away other because

of the explosion, this is know as the Big Bang Theory .

OTHER CELESTIAL OBJECTS Asteroids- There is a large gap between the orbits of Mars and Jupiter. A large number of rocks called asteroids lie in this space. The

largest asteroid is Ceres ( diameter 1003 km ).

Comets- Comets are celestial objects that revolve around the sun in very long periods of revolution. A comet appears like a ball of fire with a long bright ‘tail’ as it approaches the sun . The tail always points away from

the sun , and its size increases as it approaches the sun. The famous Halley's

comet appears

After every 76 years. It last appeared in 1986.

Meteors- Meteors are small objects made up mainly of stones present in space. They

regularly enter the earth’s atmosphere. As a meteor enters the earth’s surface at high

speed , it is heated by friction with air , and in most cases it burns to ashes in a very short

time . As it heats up and burns it appears as a glowing streak of light and is called shooting

star.

Meteorites- If a meteor is large , it may fall on earths surface before being completely burnt

out. Such meteors are called meteorites.

THANK YOU FOR WATCHING !!

Zainul- 8a