The Sun

The outer layers of the Sun rotate at a different rates to the core. At the Sun's equator the surface rotates once overy 25.4 days. Near the poles it's as much as 36 days. This is because the Sun is not a solid body like Earth. Similar effects are seen in the Gas Planets. It's differential rotation extends down into the interior of the Sun, but the core rotates as a solid body.

The surface of the Sun is called the photosphere and is at a temperature of 5800K. Sunspots are 'cool' regions on the photosphere, at a temperature of only 3800K. They are dark spots on the surface of the Sun and can be up to 50,000 km in diameter. Above the photosphere is the chromosphere. The region above the chromosphere, called the corona, extends millions of kilometers into space but is visible only during eclipses.

As well as heat and light, the Sun also emits a low density stream of charged particles (mainly protons and electrons) known as the 'solar wind' and propogates throughout the Solar System at around 450 km/sec. The solar wind and the much higher energy particles ejected by solar flares can have dramatic effects on the Earth ranging from power line surges to radio interference and the beutiful aururo borealis.

The Sun is around 4.5 billion years old. It has used up about half of the hydrogen in it's core. It will continue to radiate 'peacefully' for another 5 billion years. Eventually it will run out of hydrogen fuel and will be forced to use helium, and will eventually destroy Earth and create a planetary nebula.