The Sun
The Sun is a yellow dwarf star (G2V), about 4.6 billion years old, and the dominant gravitational force in the Solar System. It has a diameter of roughly 1.4 million kilometers and contains around 99.8% of the Solar System’s mass. Nuclear fusion in its core converts hydrogen into helium, producing energy that warms the planets. Above the core lie the radiative and convective zones, followed by the visible photosphere (~5,500 °C), the chromosphere, and the much hotter corona (~2 million °C).
Source: science.nasa.gov
APODs including "The Sun"
ERAST Pathfinder-Plus: Daedalus Defied
12/08/1998
Daedalus warned Icarus that if he flew too high, the Sun would melt his wings. Apparently, nobody gave the ERAST Pathfinder-Plus aircraft a similar warning. Earlier this month, not only did Pathfinder-Plus fly higher than any previous propeller-driven aircraft - its wings converted sunlight into power. Pictured, Pathfinder-Plus is flying above Hawaii soon after soaring to a record height of 24,700 meters. What's more, Pathfinder-Plus is only a prototype -- future aircraft in the ERAST program may fly higher. Pathfinder's wings spread nearly 30 meters, and its total mass is only about 270 kilograms. NASA's Pathfinder-Plus is flown by remote control, and can stay aloft for weeks at a time.