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"
Solstice to Equinox Cubed
26/03/2016
This 3 month long exposure packed the days from December 22, 2015 through March 20 into a box. Dubbed a solargraph, the unconventional, unfolded picture was recorded with a pinhole camera made from a cube-shaped container, its sides lined with photographic paper. Fixed to a single spot for the entire exposure, the simple camera recorded the Sun's path through Hungarian skies. Each day a glowing trail was burned into the photosensitive paper. From short and low, to long and high, the trails follow the progression from winter solstice to spring equinox. Of course, dark gaps in the daily sun trails are caused by cloud cover. Sunny days produce the more continuous bright tracks.