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"
Jupiter Over the Mediterranean
07/09/2009
This vacation included a sight to remember. Pictured above, a picturesque starscape capped a serene seascape as seen from Turkey this past August. In the above digitally stitched panorama, the Gelidonya Lighthouse shines in the foreground before a calm Mediterranean Sea. On the left, Jupiter is the brightest point in the image and since on the same side of the Sun as the Earth, was near its yearly brightest. Glowing just shy of magnitude -3, Jupiter was brighter than any star in the sky, and brighter even than Mars was during its famously bright opposition of 2003 August. On the right, the band of the Milky Way Galaxy fades into distant atmospheric haze above the horizon. Jupiter is nearing the closest part of its elliptical orbit to the Sun and so will appear even brighter during its next opposition in 2010 September.