How do we know what our sun is made off, as we can't go near it? Are we just guessing

Scientists are NOT '"guessing". Scientists know what the Sun is made of because they have and can compare the spectrums and spectrographs of the Sun to spectrographs of gases in laboratories. Helium wqas found AND NAMED becaused of a spectreaophs of sunlight BEFORE helium was found and onfirmed to be on Earth.

infohost.nmt.edu/...%20Pape's%20Solar%…

Milly, that's an excellent question. Decades ago, people 'just presumed' that the moon was made of cheese, as that's all we could relate to. Of course, those theories were debunked when man finally travelled to the moon and discovered that it was actually made of moon.

I doubt man will ever travel to the Sun, so we may never be sure what it is made of. But I can guarantee you the sun isn't made from cheese! If anything, it's likely to be a mixture of hot chilli powder and aviation fuel.

The composition of the Sun is known in great detail through spectroscopy. The Sun's light is fed into a spectroscope and broken down into a spectrum. Each element leaves characteristic "footprints" in this spectrum. The gas helium was actually discovered first by its spectrum on the Sun, and only later created in a lab on Earth.

The solar spectrum was first studied by Fraunhofer 198 years ago.

[Edit] James, no one EVER believed that the Moon was made of cheese. That's a fable invented to show how gullible people can be.
http://en.wikipedia.org/wiki/The_Moon_is…

The sun is hot. When things are hot they give off light in a pattern that can be detected at a distance. Obvious examples on earth are the yellow of sodium when salt is put in a flame or the green of copper.
So we study the sun under various conditions (like during an eclipse) and detect the materials in it.

I had looked at the spectrum of helium, hydrogen, and sodium at the laboratory.