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
31/07/2016
Filaments sometimes explode off the Sun. Featured, a huge filament had been seen hovering over the Sun's surface for over a week before it erupted late in 2010. The image sequence was taken by the Earth-orbiting Solar Dynamics Observatory (SDO) in one color of ultraviolet light. The explosion created a Coronal Mass Ejection that dispersed high energy plasma into the Solar System. This plasma cloud, though, missed the Earth and so did not cause auroras. The featured eruption depicted how widely separated areas of the Sun can sometimes act in unison. Explosions like this will likely become less common over the next few years as our Sun goes through a Solar Minimum in its surface magnetic activity.