well if the sun emits with a fusion rection,how did it ever start??

Answer 1

The fusion reaction needs high temperatures and high pressures to happen. The gasses that formed the sun were originally spreadout over a very large volume, but then collapsed under the influence of gravity. As they did so, the temperature and pressure built up. Since there was a quite a lot of this gas to begin with, the gravity was able to cause it to collapse until the temperature and pressure were at the place that fusion happens spontaneously. The fusion reaction uses hydrogen and produces helium. Once the hydrogen fuel has been consumed enough, the fusion reaction will stop from lack of fuel.

It should be pointed out that there was at least one generation of stars before the sun was formed. The previous generation produced most of the heavier elements like carbon and oxygen from which we are made. We are truly star-dust.

Also, we can see a similar process of collapse today in many nebula (which are large volumes of gas and dust). See the pictures at the following site:

http://hubblesite.org/newscenter/newsdesk/archive/releases/1995/44/

Answer 2

A fusion reaction is caused by tremendous (no, bigger than that) heat and pressure causing elementary particles (called "atoms") to collapse and combine. A fusion bomb is a close to true alchemy as we have yet achieved ... turning hydrogen into helium. The particles that are not needed in the new atom are released, which is what puts the bang in an H-bomb (thank you, Mr. Teller).
How it started is a dang good question, and "god" might be just a good an answer as any right now, since recent attempts at time travel have failed miserably. Theory says that the matter "condensed" out of the amorphous clouds of particles left over after the Big Bang, but that would tend to run counter to the tendency of matter and energy to seek maximum dispersion (entropy).
So who knows ... perhaps there were gravitational vortices in the first years of the universe ... perhaps there were wandering singularities that formed the core of stars ... perhaps it was a deity, who decided to tidy up the mess.
But basically, a whole lot of stuff compressed down until it began to fuse, release all kinds of radiation and creating heavier elements. And we call that "sunshine."
Yup.

Answer 3

A lot of God as an answer... plain defeatist attitude... if you cannot exercise your grey cells enough, the answer is GOD, what crap!

There was a mention about entropy in the answer - well, entropy also increases with heat, higher the temperature, more entropy. So, large masses of gasses in space collapse to a center, due to gravity. As that happens, the temperature of the gas goes up (temperature is greater random speed of molecules), and at some point, the collapsing gas pressure is so high, that attoms begin to collapse onto each other - fusion. Fusion reactions are exothermic - two particles fuse to produce a particle, slightly less in mass than the first two particles + energy/ radiation.

Thus, gravitational collapse of gasses started fusion reaction.

Answer 4

It most likely started when two massive particles were gravitationally attracted to each other. The collision resulted in the initial fusion reaction, and there has been enough fuel to maintain that reaction throughout the centuries.

Answer 5

I don't know. But one of the answers that others have given that it is due to gravitational attraction of large clouds. I don't believe that. In empty space, since the pressure exerted by vacuum is zero, any gas in empty space will expand, rather than contract. Furthermore, to start fusion reactions, you need high temperature (unless you believe in cold fusion). High temperatures will again cause gases to expand than contract.

We have observed gaseous clouds, and as far as I know, we have only observed them expanding. Could someone please give me some observational data of large clouds contracting? Perhaps 2 photos of a large gaseous interstellar cloud taken 10 years apart?

Answer 6

A cloud of hydrogen atoms came together through gravity. The closer they got together, the stronger the gravitational force etc. etc. until the atoms actually fused into helium.

It will stop in most cases when there are no more hydrogen atoms to fuse.

Answer 7

I thought it was because it is just so big and massive that matter is just collapsing in on itself so hard that the atoms fuse.

If that's true, then the puzzling question is why do they think it will someday stop?

Answer 8

God

...oops I offended some people

Answer 9

God created everything! :)
I'm so happy I know the answer! Now YOU just have to believe me. What have you got to lose?....

Answer 10

a spark