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"
Cold Dust in the Eagle Nebula
14/09/2001
Stars are born in M16's Eagle Nebula, a stellar nursery 7,000 light-years from Earth toward the constellation Serpens. The striking nebula's star forming pillars of gas and dust are familiar to astronomers from images at visible wavelengths, but this false-color picture shows off the nebula in infrared light. Data from ESA's Infrared Space Observatory satellite (ISO) was used to construct the detailed two color image, dominated by infrared emission from clouds of interstellar material at temperatures below -100 degrees Celsius. Blue colors highlight emission thought to indicate the presence of complex carbon molecules, known on planet Earth as PAHs, while red colors trace emission from cold, microscopic dust grains. Hot young stars are formed as this frigid material condenses under the influence of gravity. Once begun, the process takes only tens of thousands of years for truly massive stars and up to tens of millions of years for low mass stars like the Sun.