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"
The Swirling Core of the Crab Nebula
08/07/2016
At the core of the Crab Nebula lies a city-sized, magnetized neutron star spinning 30 times a second. Known as the Crab Pulsar, it's actually the rightmost of two bright stars, just below a central swirl in this stunning Hubble snapshot of the nebula's core. Some three light-years across, the spectacular picture frames the glowing gas, cavities and swirling filaments bathed in an eerie blue light. The blue glow is visible radiation given off by electrons spiraling in a strong magnetic field at nearly the speed of light. Like a cosmic dynamo the pulsar powers the emission from the nebula, driving a shock wave through surrounding material and accelerating the spiraling electrons. With more mass than the Sun and the density of an atomic nucleus, the spinning pulsar is the collapsed core of a massive star that exploded. The Crab Nebula is the expanding remnant of the star's outer layers. The supernova explosion was witnessed on planet Earth in the year 1054.