The Sun is a star, which by the effects of its size, dominates the whole of our planetary system, including the Earth.  It is the energy of the Sun which supports all of the life on Earth, because all foods and fuels come ultimately from plants using the energy of sunlight.  Because it is a star and is so close to Earth the

Sun allows scientists to study the make-up and behaviour of stars in a unique way.  No other star can be studied in such detail.  The next closest star is 4.3 light years (40,000,000,000,000 km) away.  To be able to see useful features on this star you would need a telescope 30 km in diameter.  Such a telescope would also need to be in space, like the Hubble Space Telescope, in order to avoid atmospheric distortions.

The Sun is thought to be approximately 4.6 billion years old.  Its surface temperature is about 9,300 degrees Fahrenheit and the temperature at the centre of the core is approximately 29,000,000 (29 million) degrees Fahrenheit.
The diameter of the Sun is 1.4 million km.  It is made almost entirely of hydrogen and helium with traces of at least 70 other elements.  There is enough hydrogen left in the Sun's core to last another 4.5 billion years.

The highly rarefied region above the chromosphere, called the corona, extends millions of kilometres into space but is visible only during eclipses (left). Temperatures in the corona are over 1,800,000 degrees Fahrenheit.

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