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"
Zimbabwe Sunset
21/06/2002
Today's scheduled geocentric astronomical event is the Solstice, with the Sun reaching its northernmost declination at 13 hours 24 minutes Universal Time. For denizens of planet Earth this Solstice marks the beginning of Summer in the northern hemisphere and Winter in the south. Of course, the tilt of the Earth's axis of rotation (and not a change in the Earth-Sun distance) is mainly responsible for the changing seasons and the Sun's yearly north-south motion through the sky. Following the rising and setting points of the Sun along the horizon is one way to track the Sun's progress along its seasonal cycle. Tall grasses and tinted clouds frame this dramatic view of the setting Sun approaching the northern limit of this year's seasonal journey as seen near Raffingora, Zimbabwe.