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"
Aurora over Maine
17/09/2014
It has been a good week for auroras. Earlier this month active sunspot region 2158 rotated into view and unleashed a series of flares and plasma ejections into the Solar System during its journey across the Sun's disk. In particular, a pair of Coronal Mass Ejections (CMEs) impacted the Earth's magnetosphere toward the end of last week, creating the most intense geomagnetic storm so far this year. Although power outages were feared by some, the most dramatic effects of these impacting plasma clouds were auroras seen as far south as Wisconsin, USA. In the featured image taken last Friday night, rays and sheets of multicolored auroras were captured over Acadia National Park, in Maine, USA. Since another CME plasma cloud is currently approaching the Earth, tonight offers another good chance to see an impressive auroral display. Almost Hyperspace: Random APOD Generator