how do scientists know that nuclear fusion is going on in the sun?

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Im guessing no one has gotten close enough to the sun to check. So how do they know for sure?

In: Physics

4 Answers

Anonymous 0 Comments

Another point worth mentioning to some of the other comments is that the Sun is far too low density to be anything but a nuclear reaction.

the Sun is much more massive than the earth, but the earth is much denser than the Sun. The only way for the Sun to stop becoming much, much denser is if something is counteracting gravity.

the Sun is so massive that nothing but a very exothermic nuclear reaction could counter that much gravitational collapse. In fact, every single nuclear bomb ever made by humans, multiplied by a million, detonated every single second in the center of the Sun, would not be enough to stop the Sun from collapsing. There really is nothing else but a constant nuclear fusion of hydrogen that could explain the low density of the Sun.

Anonymous 0 Comments

We don’t know anything for sure. We can only make models based on what we’ve previously observed and make predictions from that model. If the predictions we make are accurate then that gives us evidence that the model is correct. If we observe something that contradicts the model then we know that the model is not accurate or there is another unseen factor at play. We are pretty sure that fusion is going on inside stars because most young stars we see are mostly made of hydrogen based on the kind frequencies light they give off. Older stars are compromised of more heavy elements based on the frequency of their light.

Anonymous 0 Comments

Because we know the Sun is mostly made of hydrogen. We also know that there isn’t that much oxygen so that the hydrogen and oxygen would burn like here on earth. We also know that the Sun produce way too much energy to be a chemical reaction. We know how much pressure and temperature hydrogen need to achieve fusion and those work with the temperature and mass of the Sun. We can model the entire life of a star like the Sun and we can see the different stage in a lot of stars in the universe.

Sure maybe that inside the Sun there is a machine that produce the exact same temperature, mass and electromagnetic spectrum as an hydrogen star in fusion, but that seem a bit far fetch. If it look like a duck, quack like a duck, it’s probably a duck.

Anonymous 0 Comments

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