NAME : AYUSH SRIVASTAVCLASS : VIIISECTION : DAFFODILROLL NUMBER : 8108SUBJECT : SCIENCEYEAR 2013-14DATE OF SUBMISSION : 21ST

GUIDED BY : VISHNU SIR

Stars

WHAT IS A STAR ? A star is a massive, luminous sphere

of plasma held together by its own gravity.

CLASSIFICATION OF STARS A young star is called a dwarf star. It can be a

yellow star, a white star or a red star. Older Stars are called Supergiants. They can

be red star or a blue star. Stars are classified according to their

temperature and brightness into two categories :-

HOT STARS There are two types of hot stars :--

BLUE COLOURED STARS

WHITE COLOURED STAR

COOLER STARS There are two types of cooler stars :--

RED COLOURED STARS

ORANGE COLOURED STARS

HOW ARE STARS ARE BORN ? Star are formed from giant clouds of dust and

gas. From gravity, the cloud collect to form a rotating gaseous ball. Once the new star gets hot enough it begins to create energy from a process called nuclear fission. This created energy allows the star to glow for billions of years.

WHERE ARE STARS BORN ? Stars are Formed in The Eagle Nebula.

WHY DO STARS EMIT HEAT AND LIGHT ? Stars emit heat and light as they are a big

Nuclear Reactor just like our Sun.

WHY DO STARS PRODUCE WHITE COLOURED LIGHT ? Actually stars don’t produce white coloured

light they produce light which is of seven colours present in the rainbow. They combine to form white colour, this also happens with the sunlight as the sun is also a star.

WHY DO STARS TWINKLE ? Stars twinkle because of the sacks of warm

and cold air present in the atmosphere. Because of these disturbances in the path of light produced by the stars they seem to twinkle.

WHAT ARE SHOOTING STARS ? A shooting star is not a star that falls from

the sky it is just a misconception. The shooting stars are the meteoroids that burns when comes in the Earth’s atmosphere.

HOW DOES A STAR DIES ? A Star dies when it runs out of gases to burn,

first it expands into a red, super giant and it explodes.

AFTER THE STAR DIES ? When the star dies it forms a Crab Nubela.

HOW ARE STARS USEFUL ? The stars are useful to the humans in many

ways, as the Sun which provides energy to the whole Earth. And they also tell us about the directions.

FIRST USE OF STARSTHE SUN The Sun is the nearest star to our planet and

is the life source for all the living beings on earth. Without the sun no life is possible on Earth.

LIFE CYCLE OF THE SUN Our Sun is an average star. The chart below

shows the lifecycle of our sun over billions of years.

END OF THE SUN When the sun will die it will form a

black hole and the whole solar system will be destroyed when sucked into the black hole. But nothing to worry our sun is an average star and there are near about billions of years left for the sun to die.

SECOND USE OF STARSCONSTELLATIONS

The Stars help us by giving us the knowledge of a persons future(as believed by some people) and also give us the knowledge of directions.

CONSTELLATIONS The stars forming a group that has a

recognisable shape is called a constellation. There are four main types of constellations:--

Great Bear or Ursa Major or Saptarshi or Big Dipper

Orion or Hunter Cassiopeia Leo Major

URSA MAJOR It is the constellation that is found at the

early nights in summer. There are seven constant stars in this constellation. This constellation ca be used to find the pole star which is in the north direction.

ORION

Orion is the constellation that ca be seen during winter in the late evenings. It has eight bright stars. The three stars in the middle show the belt of the Hunter. The three stars show the star Sirius.

CASSIOPEIA It is a prominent constellation seen in the

northern sky during the winter in early night.

LEO MAJOR Leo is one of the constellation of the zodiac.

It forms a lion in the sky.

CONCLUSION From this presentation we came to now how

powerful the Stars are. In front of their power we are nothing. The only thing we can do is to pray to god for the long life of the Sun.