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"
A Solar Eclipse Quilt
13/11/2012
Some people are so inspired by solar eclipses that they quilt. Pictured above is a resulting textile from one such inspiration. The 38x38 inch quilt offers impressions of a total annular eclipse, when the Moon is too far from the Earth to cover the entire Sun, witnessed in Spain in October of 2005. Today, however, a full total solar eclipse will occur, although it will only be visible to eclipse chasers and those who live in a thin swath of Australia. For a few minutes, those near the center of the eclipse path will see the entire Sun blocked by the Moon, causing the day to become unusually dark. Just before -- and just after -- totality occurs, sunlight may stream between mountains on the Moon's edge creating a diamond ring effect. The next total eclipse of the Sun will occur in November 2013.