Why stars getting bigger, devouring planets and many other celestial objects that orbiting itself? And why collapses on itself after getting big
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A star is essentially a very long lasting explosion in space, so they are experiencing 2 forces essentially – the outwards push of the explosion making the start want to “blow up” and an inwards pull due to gravity. Those two forces will form a balance that makes the star a certain size – the outer edge of the star is trying to “blow away” but getting pulled back towards the center of the start by gravity.
Forget the devouring stars and stuff part, that’s not really applicable here.
What happens is that as stars age, they are changing their fuel source and it’s a bit complicated because many different things *can happen*. Think of it this way, a star burning fuel is like 2 kids left alone in the kitchen. They’ll begin with the candy & chocolate, high energy “easy” food, then maybe they’ll switch to bread, still high energy but less desirable, then they start getting desperate and target the lesser foods, fruit, vegetables, etc. S*ometimes* something special happens, one kid is double checking the cabinets and drawers maybe discovers a hidden cookie or something during the fruits and veggie stage while the other is stuck eating radishes.
In the star once the “candy” is done, the star stars switching the “bread”, this is less energy for the star so the gravity part is still strong, but the outward explosion is less strong so the star starts to shrink. Since the color of the star is related to the energy it’ll also start changing colors as well. So the star (kid 1) is actually shrinking inside because it has less explosion, BUT then the outer part of the star (kid 2) discovers some cookies in some high up cabinets. It’s a bad metaphor I guess, but what is happening is the “inside” of the star is shrinking but the “outside” of the star eats the cookie and gets energy and starts expanding again. You get a funky star with a dense inner part (eating vegetables) but a really large and spread out outer part (that’s eating the cookie).
If the star didn’t have the cookie it just gets smaller and smaller (meaning denser) and becomes a dwarf. If the star has enough cookies it’s gets bigger and bigger and turns into a giant.
Eventually the cookies all get eaten too and the star has very little explosion left and the gravity pulls it back down inside. T[he result is basically like this experiment](https://www.youtube.com/watch?v=2UHS883_P60) the star collapses down super quickly and then blows back out super quickly. That’s a supernova.
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