Sun Facts

recall the Sun’s diameter (1.4 million km) and its distance from Earth (150 million km)
recall the temperature of the Sun’s photosphere (5 800 K)
describe the solar atmosphere (chromosphere and corona) and recall the approximate temperature of the corona (2 million K)

There are at least 100 billion stars in the Milky Way and our Sun is just one of them. As stars go it would be classed as a dwarf. It is composed of out 3/4 hydrogen, about 1/4 helium and small amounts of other elements.

The Sun has a diameter (ignoring the corona) of 1,400,000 km. that's about 107 x bigger than the Earth's and about 20 x bigger than Jupiter's. The average distance from the Earth to the Sun (known as 1 AU) is 150 million km.

The outside of the Sun is made up of three distinct regions

The Corona
Corona means crown. This is the outermost part of the Sun. It can only be seen directly during a total solar eclipse. Temperature up to 2 million degrees. Scientists are not sure as to why it is so hot.

The Chromosphere
(2,500 km) Means coloured sphere. This is responsible for the absorption spectrum we will discuss later. Temperature up to 400,000K.

The Photosphere
(450 km) Means sphere of light. The visible surface of the Sun. Visible light from the Sun originates here. Temperature about 5,800K.

Temperature

Scientists often measure temperature in Kelvin. Don't worry too much, to get from degrees Centigrade to Kelvin you just add 273. When we're talking about very high temperatures there's very little relative difference between the two.