There is nothing remarkable about our sun in the scheme of things. It is very similar to millions of other stars (and our sun is a star) in the universe. You might even call our sun an "average" star.
The energy source for our sun is nuclear fusion. If the total energy output of the sun for just one second could be captured, it would provide the United States with enough energy at the current level of usage for nine million years.
There is a hard core at the center of the sun. The core is so dense and the sun is so large that energy released in the center of the sun takes 50 million years to reach the surface. That means that if the sun suddenly stopped producing any energy at all at the core today, it would be another 50 million years before we noticed it here on earth.
Our sun has been producing radiant and thermal energy for the last four or five billion years. There is enough hydrogen for it to continue producing energy for at least another hundred billion years. In about 10-20 billion years, the sun will begin to expand. It will engulf the closest planets (including Earth), and then it will be a giant red star. In another few billion years after that, our sun will become what is known as a dwarf star.
Most people think of the sun as this large (huge), constant featureless fireball in the sky. The large part is right, but the constant (or steady) and the featureless parts are all wrong. Sunspots are a feature of the sun that was first noted by Theophrastus about 325 BC. A moderate-size sunspot is about the size of Earth. Sunspots come and go over a period of days or weeks.
