How do we know anything about any astronomical things to make theories about the universe?

Question

How do we know what a supernova is? How do we know black holes exist? How do we know what a neutron star is made of or if they exist? How do we know what the sun is made of even though we cant get to it. Basically how can we know anything about anything outside of earth thats so many lightyears away if we cant see it at all but know so much....?

Answer 1

We know about distant things by comparing what we see, or how we see them to the things we have here on earth and applying theories for laws of physics. For ex. when we see a distant nebula that emits some color of light, we can compare it to the color of known gasses and thus know what its composed of. The same rule applies to sun, stars and other things.
Observations of space do not limit to visual light only. One can measure different forms of radiation and so on.
We can know if the distant body is moving (in respect to Earth) by measuring the Doppler effect on the light it emits.
Now, supernovas are stars, that explode and end their life by emmiting large amount of light and other radiation. We know that they exist because we can observe them as they expolode above our heads. Scientists have created theories that model the behaviour and dynamic of gasses that compose a star. The theory predicts that at some point the star ends its fuel and this starts a chain of reactions that end in supernova. The basic process is: you see something, you try to understand how it works by creating a theory, and you test your theory by comparing it with your observations.
Please note that we do not have "the final theory of universe", that means we do see lot of things that we don't fully understand and existing theories can't explain how they work. Thats why there is still a progress in astronomy and physics. We create better theories every day and our goal is to find the "final theory" that would explain absolutly everything.

We can observe black holes indirectly by observing the gravitational lens effect they create (see sources).

Neutron star is a dead star leftover after some massive star goes supernova. The theory that models star life predicts that after the star of certain mass dies it will create supernova. Now all is left is to look for an object that matches the theory.

Answer 2

They know about the chemical compensation of the sun by analyzing the spectra of light coming from it. Certain elements absorb or emit light of of a certain wavelength (color). The sun also has sound waves (caused by all of that turbulence) constantly traveling trough it, so by watching the surface move back and forth, they can make guesses about the internal composition of the sun by timing the sound waves as they penetrated the sun and emerge on the other side. They also analyze other types of energy (x-rays, neutrinos, etc.) emitted by the sun.

A lot of astronomical objects, such as black holes and neutron stars, are predicted by physical theories, like Einsteins' theory of relativity. They can them make observations of known objects to see if the observations match the theories.

Since you cannot see a black hole, you can figure out where one should be by watching the stars that are orbiting the hole. By estimating the mass of the star, and comparing the mass (inertia) of the star with its speed, one can figure out how much gravity is required to keep it in its orbit. That tells you the mass of the black hole.

Neutron stars tend to give off radio waves, and are called "pulsars". They have been observed by radio telescopes since the 1950s or 1960s.

Answer 3

No offense, but did you actually pay attention to anything the teacher was saying in either of your chemistry or physics classes? We have these things called the chemical elements here on earth. Each element exhibits certain characteristics. By seeing these characteristic traits in celestial things, we can determine what those things are made of. As far as how they work, we understand, thanks to people like Chadwick, Rutherford, Fermi and lots of others, what atoms are made of and what happens when you smash two or more atoms together to make a new atom i.e. fusion [which is what makes stars shine], and what happens when you use a particle to break another atomic nucleus apart i.e. fission [which is what nuclear reactors in power plants do]. Plus, we also know that the laws of chemistry and physics apply everywhere in the universe cause if they didn't the universe wouldn't be what it is and we wouldn't be here to observe it.

Answer 4

That's a BS in astronomy right there. Try getting an intro astronomy textbook out of the library and reading up on how we figure that stuff out. It's all pretty straight-forward, it's just too long to explain here.

Answer 5

Please go read a book on Cosmology or at least type your question in Google and find an answer for yourself. You few questions about summed up the entire field of Cosmology and Astronomy.

Answer 6

Telescopes and spectrometers.