Notes, Exercises, Videos, Tests and Things to Remember on Stars
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The star are self glowing heavenly bodies which generate the energy themselves by nuclear fusion reaction. The temperature of stars is very high. About 3000 stars can be seen in the skyinclearnight with naked eyes.The sun is the nearest star of earth. Alpha centauri is the nearest star of the sun.
Scientist believed that stars are formed by the nebula. The nebula will make the collection of inter seller objects into various places into smaller parts. By any means, any one of the mass will develop the gravitational force and stars to attract the other patches towards itself. As a result of which its mass increases and the pressure on the circle also increases. And when the temperature of center reaches 5 x 106 degree Celsius then it is called a protostar .In protostar gradually nuclear fusion reaction starts, due to excessive gravitational force, and it converts into stars.
When hydrogen changes to helium (41H1→ 2H4) tremendous energy is released. This energy is used to keep stars shining. When hydrogen is finished, there is no more production of heat. When outside pressure decreases, the gravitational pull causes the star to contract. Due to contraction, the temperature of the outer core increases. This results in the expansion of the outer layers and increase in the size of the star. The expansion causes the temperature of the outer layers to fall and thus the stars becomes very large in size and red in color (also called, a red giant).
Black hole is an object with highest density and such a great force of gravity that can even attract light, that is, even light cannot come out of this object. When hydrogen gets exhausted, extremely large stars contract as a result of the gravity and protons and neutrons start to come together. The force of gravity become so large that even light cannot escape from it.
When hydrogen gas exhausted extremely large stars contract as a result of the gravity and protons and neutrons start to come together. The force of gravity becomes so large that even light cannot escape from it and it appears as a black hole.
At night some stars look brighter than the other. There are two factors that determine the brightness of any star- size and distance from the earth. Those stars that look brighter are either bigger stars or are closer to the earth. The closest star is the sun. That's why it is the brightest.
The stars contract continuously as hydrogen goes on decreasing. This results in the increase in temperature and pressure of the core. The surface heat and pressure decrease and the stars expand. These very large- sized stars that are red in color are called red giants.
The two specific characteristic of black hole are:
The four differences between a star and a planet are:
The giant family of sun including planets, asteroids , comets etc is called ______.
The nearest star to the sun is ______.
Which is the largest satellite in our solar system?
The planet having shortest orbit is _______.