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"
Ecliptic New Zealand
10/07/2010
Four bright celestial beacons and a faint triangle of light follow the plane of the ecliptic as it arcs high through this southern hemisphere night skyscape. Seen on a July winter night from Lake Taupo on New Zealand's North Island, the line-up features Venus, Regulus (alpha star of Leo), Mars, and Saturn from lower left to upper right. Just put your cursor over the picture to identify the planets and constellations. The delicate luminous glow of Zodiacal Light, sunlight scattered by dust along the ecliptic, also rises above the horizon from the lower left. Of course, defined by the path of the Sun through planet Earth's sky, the ecliptic plane rides low during July nights in the northern hemisphere's summer skies. Tomorrow, the Moon and Sun will meet on the ecliptic. Along a track across the southern Pacific Ocean, the daytime sky will feature a total solar eclipse. Total Solar Eclipse: Times and Visibility | Webcast