Aug 4

Elements of our Galaxy

A Galaxy is an intensive collection of stars, glowing nebula, gas and dust united by gravity. Scientists believe that is a black hole, which is the remains of a massive star, is situated at the centre of many the galaxies. The galaxy that contains our solar system is called the Milky Way. There are several elements that form our galaxy. Facebook

1) Galaxy dust
The space between the stars is filled with gas and tiny pieces of solid particles or dust. Most of these gas and dust result form the death of stars, which either exploded or blue of their outer layers, returning their material to space.

2)Spiral arms
The Milky Way has spiral arms coming out of its central bulge following their own path.The take several hundred million years to .complete their orbit.

3)Star nursery
Stars are formed within clouds or hydrogen gas. A part of the cloud then forms a dense ball of gas. More gases extracted because of gravity, thereby compressing the ball into the tighter and hotter mass. As a result, a nuclear fusion is triggered,which converts hydrogen into helium and radiates energy as a very bright star.

4)Hot blue star
Stars get their colour depending on their temperature. The coolest star appear red, while the hottest ones are blue. For a star, its temperature is determined by its mass of the Sun or even more . Interestingly, whether a star has 10 times the mass of the Sun or 150 solar masses,it appears blue to our eyes.

5)Solar system
Our solar system was formed about 4.6 billion years ago. It includes the eight planets and their natural satellites, dwarf planets such as Pluto and Ceres, asteroids, comments and meteoroids. The sun contains almost all the mass present in the solar system and exerts the tremendous gravitational pull on the celestial bodies.

6)Central bulge
In a spiral galaxy such as the Milky Way the stars, gas, and dust organized into a “bulge” and “disc”, containing “spiral arms” and a “halo”. The bulge is a round structure primary Lee made of old stars, gases, and dust. The outer parts of the bulge are difficult to distinguish from the halo. The bulge of the Milky Way is roughly 10,000 light-years across.

Black holes are huge but surprisingly cover only a small region. Because of their mass, they have an extremely powerful gravitational force. Nothing can escape them; even light is trapped by a black hole.



Black holes have three layers: the outer and inner event horizon, find the singularity. The event horizon of a black hole is the boundary around the mouth of the black hole, where light loses its ability to escape. The singularity lies at the centre of the black hole. It is a one dimensional point that contains infinite mass in a considerable small space.

8) Dark matter
dark matter is a kind of matter that cannot be seen using telescopes. However, it accounts for most of the matter in the universe. The existence and properties of dark matter are inferred from its gravitational effect on visible matter, radiation and the large scale structure of the universe. Dark matter accounts for 23% of the universe.

– compiled by

Madhurani Chavan,

Upper Primary Student

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