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"
6 Years of Saturn
04/09/2009
Today, planet Earth passes through the plane of Saturn's rings. From the perspective of earthbound astronomers, Saturn's rings will be edge-on. The problem is, Saturn itself is now very close to the Sun, low on horizon after sunset, so good telescopic images will be difficult to come by. Still, this composite of Saturn views taken from 2004 - 2009 (lower right to upper left) illustrates the change in ring tilt over the last six years and includes a nearly edge-on ring view, based on images captured earlier this year. While Saturn's south pole is clearly seen in the sequence, particularly at the lower right, it will be hidden in the coming years. Saturn's north pole will be increasingly visible, along with the tilting rings, as the planet emerges this fall in the predawn sky.