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"
The Moon & Venus Over Geneva
19/06/2002
The Moon, fresh from a biting encounter with the Sun last week, appeared next to threaten Venus. The waxing Moon appeared to glide right past, however, just a few degrees away. Venus, of course, is much further away from the Earth than the Moon, so the passing was really just an angular illusion. Pictured above on June 13, a fading sunset finds the crescent Moon and Venus between clouds and above the city lights of Geneva, Switzerland.