When this happens, it will have become a white dwarf. It will keep its enormous mass with the approximate volume of our planet.
The sun has an ‘atmosphere’ that retains the heat. The closer that you get, the hotter it gets. The immense amount of heat radiates outwards, in the same way that you feel the heat from a room heater. This is hot enough to instantly vaporize anything before it had a chance to even come close to it. This intense pressure creates heat at temperatures that are around 15 million degrees C. When our sun burst into creation, it was a mass of swirling gases that included a core or center that is compressing atoms together in a process called ‘nuclear fusion’. To someone way out there, our sun would look like a star as well. When you look out into the stars you are actually seeing the suns of other solar systems. Heat on the sun has a very complex journey process. So you might wonder what causes the sun to create so much heat. This heat expands into the solar system and the farther away it gets, the cooler it is. The sun is a sphere of hot gases that burn and give off heat that warms. The earth is in our solar system in just the ‘right’ position so that we aren’t too close to the sun to get burned to a crisp and not too far away to become a planetary snowball. Our sun is the main reason that we have life on our planet.