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"
Conjunction at Sunset
29/12/2011
While Comet Lovejoy entertained early morning risers in the southern hemisphere, a lovely conjunction of a young crescent Moon and Venus graced western skies at sunset. Captured on December 26th the conjunction, with beautiful sunset colors above and below, is seen here over Viverone Lake near Turin, Italy. But if you've been outdoors at all lately enjoying sunsets on planet Earth, then you've probably noticed Venus low in the west as the season's brilliant evening star. Sometimes mistaken for a terrestrial light near the horizon, Venus is the third brightest celestial beacon, after the Sun and Moon. That distinction is particularly easy to appreciate in this peaceful scene.