The Sun is the star that is located at the center of our Solar System. It is located in the Milky Way galaxy, and it lies on the Main Sequence of the H-R diagram. It is considered a low-mass star. The sun has existed for billions of years because it has a maintained balance between pressure and gravity. This is called Hydrostatic Equilibrium. Energy is made in the core of the sun. Then, it moves from the inner most part of the sun to the surface. First, it moves through the radiative zone, which makes up 70% of the sun. Then, it moves through the convection zone. The convection zone is too dense for radiative transfer, so it must resort to convection transfer.
The sun's atmosphere is made up of three layers: the photosphere, chromosphere, and the corona. The photosphere is the surface of the sun. This is where surface temperature is determined. Above the photosphere is the chromosphere. It has an unexpectedly higher temperature than the photosphere. Then, the corona is the extended layer of gas above the chromosphere. It is extremely hot, but it has an extremely low density. It is so hot that it emits x-rays.
The sun's atmosphere is made up of three layers: the photosphere, chromosphere, and the corona. The photosphere is the surface of the sun. This is where surface temperature is determined. Above the photosphere is the chromosphere. It has an unexpectedly higher temperature than the photosphere. Then, the corona is the extended layer of gas above the chromosphere. It is extremely hot, but it has an extremely low density. It is so hot that it emits x-rays.