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"
Sungrazer
22/03/2009
The Sun destroyed this comet. Arcing toward a fiery fate, this Sungrazer comet was recorded by the SOHO spacecraft's Large Angle Spectrometric COronagraph(LASCO) on 1996 Dec. 23. LASCO uses an occulting disk, partially visible at the lower right, to block out the otherwise overwhelming solar disk allowing it to image the inner 5 million miles of the relatively faint corona. The comet is seen as its coma enters the bright equatorial solar wind region (oriented vertically). Spots and blemishes on the image are background stars and camera streaks caused by charged particles. Positioned in space to continuously observe the Sun, SOHO has now been used to discover over 1,500 comets, including numerous sungrazers. Based on their orbits, they are believed to belong to a family of comets created by successive break ups from a single large parent comet which passed very near the Sun in the twelfth century. The Great Comet of 1965, Ikeya-Seki, was also a member of the Sungrazer family, coming within about 650,000 kilometers of the Sun's surface. Passing so close to the Sun, Sungrazers are subjected to destructive tidal forces along with intense solar heat. This comet, known as SOHO 6, did not survive.