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"
Cosmic Crab Nebula
25/07/2014
The Crab Pulsar, a city-sized, magnetized neutron star spinning 30 times a second, lies at the center of this tantalizing wide-field image of the Crab Nebula. A spectacular picture of one of our Milky Way's supernova remnants, it combines optical survey data with X-ray data from the orbiting Chandra Observatory. The composite was created as part of a celebration of Chandra's 15 year long exploration of the high energy cosmos. Like a cosmic dynamo the pulsar powers the X-ray and optical emission from the nebula, accelerating charged particles to extreme energies to produce the jets and rings glowing in X-rays. The innermost ring structure is about a light-year across. With more mass than the Sun and the density of an atomic nucleus, the spinning pulsar is the collapsed core of the massive star that exploded, while the nebula is the expanding remnant of the star's outer layers. The supernova explosion was witnessed in the year 1054. Participate: Take an Aesthetics & Astronomy Survey