Gas diffusion in space.


Hey all,

I was wondering about how stars are made from gas clouds. Shouldn’t gas always diffuse within the container it is in? In this case, diffuse into space?

So how do gas clouds accumulate enough mass to form a star, instead of all gas diffusing into empty space?

Thanks for any insights!

In: 2

5 Answers

Anonymous 0 Comments

Diffusion is just part of the things that play a role in transport, you have to take into account other forces and interactions.

Anonymous 0 Comments

Gravity acts as the container. It takes cold gas, otherwise the kinetics involved keep the gas dispersed like you state. But once the gas cools enough it no longer has enough energy to hold itself apart against gravity and begins to contract. This of course starts increasing the temperature of the gas, but momentum inwards and the increasing gravity from the larger mass contracted into a smaller volume fight the outward push from the increasing heat. Eventually the heat being generated will blast away the further parts of the in falling gas that were too far away before the new star got too hot.

Edit for grammar. Typing is hard.

Anonymous 0 Comments


Even in a closed container on earth the pressure is higher at the bottom than the top because of gravity.

Do that with a big ball of gas in space and it’s enough to pull the gas tight enough to start fusion. Just like on earth, the pressure is higher as you go to the center. The star is just FAR larger.

Anonymous 0 Comments

Gravity. And some magnetism via static electricity. A cloud of gas that results in the creation of a star is ENORMOUS. We are talking 100s of times the mass of plant earth. That’s many trillions of times more particles than if every human in existence became a vape-lord and puffed 24/7.

Anonymous 0 Comments

Because of gravity. When a lot of gas is close to other gas particles, gravity is stronger than gas diffusion, allowing for stars. This is also why, more often than not, bigger planets are gas giants.