Sun

The Sun is the star at the center of the Solar System with a diameter of 1,392,000 km and it is 110 times larger than Earth and 9 times larger than Jupiter. 1 Solar radii is equivalent to the diameter of Sun. The Sun performs a complete rotation on its axis once every 26.8 days, known as the rotational period. The Sun's mass is 1.989 x 10^30 kg or 1 solar mass, which is 300,000 times heavier than Earth. Its mass consists 78.4% of hydrogen and 19.8% helium. There are smaller amounts of oxygen (0.86%), carbon (0.4%), and iron (0.15%) at the surface of the Sun, it is also known as photosphere.

The average surface temperature around the Sun is 5500 °C (5770 K). The core of the Sun has temperatures rising to 15 million °C. Inside the core, the nuclear reactions take place, i.e. hydrogen is turned to helium as the resulting energy spreads as radiation. This causes matter to move, because matter is passed to the irregular surface to the Sun while cooler matter moves towards the centre. The currents result in eruptions on the surface, creating a constant gas vortex. The Sun's atmosphere consists of three layers: the photosphere, the chromosphere and the higher extent of the corona.

Sun as a star
The Sun is a perfectly ordinary fixed star with an average size like other main-sequence stars. The distance between Sun and the galactic centre is 7,700 parsecs (25,000 light years). The Sun orbits the centre of the galaxy every 225 million years with a speed of approximately 220 km/s (kilometres per second) on a nearly circular path. Every second, the Sun transforms 4 million tons of matter into electromagnetic radiation that arrives on Earth as light, warmth, X-rays, infrared rays and ultraviolet radiation. This process has been repeated itself over since the birth of Sun, about 4.6 billion years ago, according to physical calculations of astrophysics. On the basis of their calculations, astro-physicists predict that once the Sun entire supply of Hydrogen has been transformed to Helium, as of Sun in helium burning phase, will be 10 times larger and possibly be a giant star. It will then expand into a red giant and subsequently shrink down to the size of a white dwarf that will cool out gradually.

Structure

Solar Activity

Sunlight