Eli5 Why was the sun made up of mainly just hydrogen when it was formed compared to inner planets that have so many more elements, especially higher ones?

Question

All,

I have a basic understanding that a lot of elements were brought to planets by comets, supernova explosions and so on.

Why didn’t the sun attract most of these comets and fragments from celestial explosions instead of the planets? And why was / is the sun mainly just hydrogen?

In: 105

Answer 1

Everything in the universe begins as hydrogen. Think of the sun as the universes material factory. Through nuclear fusion the sun will slowly over billions of years convert hydrogen and helium to every other element on the periodic table from number 3 all the way to our sun’s case iron. Smaller sun’s like ours hit iron and then they die because it takes more energy to go past iron then the conversion gives off. This will be when our sun goes through its last death throws and expands and takes out most of the solar system with it. Sun’s much larger than ours go through this cycle but they have such large gravitational energy they can keep going and will chug out the higher elements and then they to reach a critical point and die out and explode. Every single thing that exists in the universe was created in a star. The metal in your car from the carbon that makes up your body. All tangible matter other than hydrogen and helium was created and puked out all throughout the universe by stars. The biggest stars are the special ones. They reach a higher level of existence and then their deaths are the most spectacular events that exists. Not quite the largest stars will die in a spectacular fashion but leave their super heavy elements in their core as a super dense ball called a neutron star as they go supernova. These explosions are so large and powerful that one happened many many light years away and we could see it from earth. Even weirder are the ghosts these stars leave behind. They are crazy hot and spin rapidly and some which are called pulsars eject matter out like a laser beam. Then at the top of the universes scale are the largest giant stars that when they die they implode and they turn into black holes. And that is a whole other subject that defys everything you know about the world. So basically everything just gets recycled and will overtime find some other matter floating around and start clumping together to form planets or even get sucked in to another star or a black hole.

Edit: There is new theories that there are actually some elements that are not made by the supernova process but by in fact two of the neutron stars colliding.