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 Green Flash of Spring
09/04/2016
Taken on March 20 from the top of Haleakala on the isle of Maui, planet Earth, the first sunrise of northern spring is pictured in this vacation snapshot. The telephoto view from the volcanic caldera above a sea of clouds also captures an elusive green flash near the Sun's upper limb. Atmospheric layers with sharp temperature changes cause the colorful flash as the Sun rises behind a distant cloud bank. Refraction along sight lines through the layers creates multiple distorted images of the Sun, and for a moment, can visibly deflect shorter wavelength green light.