ABOUT GALAXIES
A galaxy is a gravity bound system of stars , or when put in simple words , a cluster of stars , combined together by gravitational force .
BUT , HOW ARE GALAXIES FORMED ?
SMALL CLOUDS OF STARS AND DUST SWIRL THROUGH SPACE . OVER A PERIOD OF TIME MORE CLOUDS OF STARS AND DUST JOIN IN AND THEN GRAVITY SENDS THEM CIRCLING AROUND EACH OTHER . AFTER THAT IT KNITS THEM INTO LARGER SPINNING PACKS , KNOWN AS GALAXIES .
ALSO , WHAT ARE THE TYPES OF GALAXIES ?
GALAXIES CAN BE CATEGORISED INTO 3 MAJOR CATEGORIES , NAMELY :-
1. Elliptical – These type of galaxies account for nearly 1/3rd of all the galaxies in the universe . They vary from being circular to being very elongated . They also contain very little gas and dust when compared to other and along with that , they contain older stars and do not actively form stars anymore .
2. Spiral – They appear as flat , blue-white discs consisting of stars , gas and dust with yellowish bulges in their centers . They can be further classified into 2 types of spiral galaxies – Normal Spiral galaxies and barred spiral galaxies . The cluster of stars moves through the central bulge in the barred spiral galaxies while the spiral galaxies consist of actively forming stars .
3. Irregular Galaxies – These galaxies have very little dust and are neither disk , nor elliptical . You can only see them as you see deeper in the universe , which is equivalent to looking back in time . They were dominating in number in the early universe .
DO GALAXIES DIE ?
Galaxies often die when new stars stop forming . When the new stars will not form , the old stars will die , leading to the death of the galaxy since a galaxy will not have any stars left .
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