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"
Eruptive Prominence
08/07/1999
Activity on our parent star continues to increase as the sun approaches a maximum in its 11-year solar cycle, expected in the year 2000. On June 14 - only a week before the solstice - the space-based SOHO observatory recorded this stunning view of an immense prominence erupting from the sun's southern latitudes (south is up). The false-color image was made in the extreme Ultraviolet light produced by ionized Helium atoms in the solar plasma. Earth dwellers fortunate enough to be well located in Europe, the Middle East, Asia may be able to view for themselves activity above the solar limb during the upcoming August solar eclipse - the last total eclipse of the second millennium.