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"
A Triple Sunrise Over Gdansk Bay
04/08/2009
How can the same Sun rise three times? Last month on Friday, 2009 July 10, a spectacular triple sunrise was photographed at about 4:30 am over Gdansk Bay in Gdansk, Poland. Clearly, our Sun rises only once. Some optical effect is creating at least two mirages of the Sun -- but which effect? In the vast majority of similarly reported cases, mirages of the brightest object in the frame can be traced to reflections internal to the camera taking the images. Still, the above image is intriguing because a sincere photographer claims the effect was visible to the unaided eye, and because the photographer took several other frames that show variants of the same effect. Therefore, polite readers are invited to debate whether the above image captures a particularly spectacular example of common reflections inside a standard digital camera, shows one of the most spectacular examples of atmospheric lensing yet recorded, or was caused by something completely different. If the discussion converges, the consensus will be posted here at a later date.