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"
A Solar Eclipse Painting from the 1700s
28/01/2008
Is this painting the earliest realistic depiction of a total eclipse of the Sun? Some historians believe it is. The above painting was completed in 1735 by Cosmas Damian Asam, a painter and architect famous in early eighteenth century Germany. Clearly drawn is not only a total solar eclipse, but the solar corona and the diamond ring effect visible when sunlight flows only between mountains on the Moon. The person depicted viewing these eclipse phenomena is St. Benedict. Roberta J. M. Olson and Jay Pasachoff have hypothesized that Asam himself may have seen first hand one or all of the total solar eclipses of May 1706, 1724, and 1733. Many facts about our astronomical universe that are taken for granted today have been known -- or accurately recorded -- only during the last millennium. Asam's painting currently hangs in Weltenburg Abbey in Bavaria, Germany.