Our sun is a star just like all the others we see in the night sky. It is just one of the billions of stars that make up the galaxy we call the Milky Way.
Our sun is a fiery ball of hot gasses that consists of three-quarters hydrogen and one-quarter helium. The surface of the Sun is about 11,000 degrees Fahrenheit, while the core is much hotter at more than 28 million degrees Fahrenheit.
The sun is about 365,000 miles across and weighs about 2,000 million trillion tons. If it were only twice its size, it would have burned out already, since larger stars burn their fuel more quickly. If it were much smaller, it would give out so little heat that the Earth would be locked in a permanent ice age and much too cold for life to survive. It is more than 170 times as big as the Earth and produces the energy necessary to allow life on Earth to exist.
The energy is produced because of the huge pressures created at its core. This forces hydrogen atoms together in a continual nuclear reaction forming helium and releasing enormous amounts of energy. Every second of the day 600 million tons of hydrogen is converted to helium.
Since its birth, about 5 billion years ago, the sun has burned through nearly half of its hydrogen fuel supply, but is expected to burn for about another 5 billion years.
Our sun is a medium sized star located on one of the Milky Way's spiral arms, some 30,000 light years out from the center. A light year is the distance transversed by light in one year moving at about 186,000 miles per second.
Our sun is far from being the oldest in the Milky Way galaxy. The Milky Way is only one of the billions of galaxies that make up the entire universe which is still growing and rapidly expanding. Andromeda, one of the nearest galaxies beyond the Milky Way, is more than 3 million light years away.
The Earth is about 93 million miles from the sun, but varies according to the time of the year. Much closer and it would be too warm for liquid water to exist, while much further away it would leave a frozen landscape. Energy from the sun drives the photosynthetic process which provides for the organisms at the base of the Earth's food chain that allows for the rest of life on the Earth.