Our sun is over 2.5 million miles around at its equator. If an airplane could stand the heat and fly close to its surface, it would take six months of flying day and night to travel around the sun.
In fact, 109 earths could fit along the diameter of the sun. Our sun is really like a giant nuclear furnace that rotates every 25 days.
It is a burning blob of gas with temperatures of 20 million degrees Celsius at its center. This atomic furnace in the sky uses this heat to make hydrogen into helium.
This process is called fusion, and it creates astonishing amounts of energy, which is poured out into space and from which we get our heat and light. This process of fusion on the sun turns 4 million tons of matter into energy every second.
And it is expected to keep right on doing it at the same level for another 5 billion years.