False colour image of the Sun, taken through a “H-Alpha” telescope. This shows a region of the Solar atmosphere known as the “chromosphere”.

The Sun is a G-type (“yellow”) main sequence star, about half-way through it’s expected life span. It formed a little under five billion years ago when a cloud of cold gas and dust came together due to the force of its own gravity. Eventually, the intense heat and pressure at the core of the collapsing cloud caused hydrogen nuclei to collide and undergo nuclear fusion to form helium, releasing an enormous amount of energy. That process powers our Sun to this day, and is expected to continue for about another four to five billion years.

Quick Stats:

  • Stellar Class:  G2V
  • Radius:  696,342 km   (109 x Earth)
  • Age: 4.6 Billion Years
  • Temperature5,500°C (Photosphere)
  • Mass1.99 x 1030 kg   (333,000x Earth)


  • The Sun is by far the most massive object in the solar system, and contains almost one thousand times more matter than everything else combined!
  • You could fit 109 Earths across the diameter of the Sun, or 1.3 million Earths inside it!
  • While the surface of the Sun is a little under 6,000°C, the core is around 15,000,000 degrees Celsius!
  • The Sun loses about 4.3 million tons of mass every second, as it is converted into energy by fusion of hydrogen into helium.
  • The outer atmosphere of the Sun, known as the “corona”, is much hotter than the surface – at several million degrees Celsius.
  • The Sun is almost perfectly round, with only about 10 kilometers difference between the polar and equatorial diameters.
  • It takes the Sun around 220 million years to complete one orbit of the Milky Way galaxy.
  • Because it is a plasma, the Sun rotates faster at the equator than at the poles, which is known as “differential rotation”.
  • Light from the Sun takes about 8 min 20 sec to reach us from the surface – but was created in the core of the Sun hundreds of thousands of years earlier.
  • As it ages, the Sun is burning more brightly, and will make the Earth uninhabitable in perhaps a billion years from now.
  • Towards the end of its life, the Sun will swell into a Red Giant star, which will be so large that it consumes Mercury, Venus, and maybe the Earth.
  • When the Sun dies, it will not go supernova. Instead it will with shed its outer layers to space  and the core will collapse into a star about the size of the Earth called a “White Dwarf”. The shed layers are known as a planetary nebula.
  • The Sun has an extremely strong magnetic field, which stores and releases tremendous amounts of energy.

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The Sun