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"
Phases of Venus
21/05/2004
Venus is currently falling out of the western evening sky. Second planet from the Sun and third brightest celestial object after the Sun and Moon, Venus has been appreciated by casual sky gazers as a brilliant beacon above the horizon after sunset. But telescopic images have also revealed its dramatic phases. In fact, this thoughtful composite of telescopic views nicely illustrates the progression of phases and increase in apparent size undergone by Venus over the past few weeks. Gliding along its interior orbit, Venus has been catching up with planet Earth, growing larger as it draws near. At the same time, just as the Moon goes through phases, Venus' visible sunlit hemisphere has presented an increasingly slender, crescent shape. Now sharing the sky with a crescent Moon, on June 8th Venus will actually cross the face of the Sun, the first such transit since 1882.