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"
An Airplane in Front of the Sun
29/01/2001
Sometimes, good planes come to those who wait. Experienced solar photographer Thierry Lagault had noticed planes crossing in front of the Sun from his home in suburban Paris. He then got the idea for the above photograph, but had to wait through many near misses. About two weeks ago, he got his wish: a jet crossed directly in front of the Sun when his solar imaging equipment was set up. The resulting image, shown above, was taken in a specific color of red light called Hydrogen-Alpha, and the picture's contrast has been digitally enhanced. Dark prominences can be seen lacing the Sun's busy surface. The airplane is an MD-11.