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Sun

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The Sun is a massive star. It sits at the center of our Solar System. It is the main source of power for life on Earth.

Highest resolution photo of Sun (NSF) as of January 20, 2020
Highest resolution photo of Sun (NSF) as of January 20, 2020

The Sun is very big. Its diameter is about 1,391,400 km. That is 109 times wider than Earth. It holds 99.86% of all the mass in our Solar System.

Sun poster
Sun poster

Deep inside the core, the Sun is very hot. The core is nearly 15.7 million Kelvin. Heat is made by nuclear fusion. This is a way that atoms join together. In the core, hydrogen turns into helium. This process makes a lot of light and heat.

Proton-proton reaction chain
Proton-proton reaction chain

Light travels from the Sun to Earth. It takes about 8 light-minutes to reach us. The Sun's surface is called the photosphere. It is made mostly of hydrogen and helium.

The life cycle of a Sun-like star (annotated)
The life cycle of a Sun-like star (annotated)

One day, the Sun will change. In about 4 to 7 billion years, it will grow much larger. Scientists call this a red giant. Later, it will become a small, cool star. We call this a white dwarf.

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🖼️ Images & Media (37)
File:Sun poster.svg
Sun poster.svg
File:Oort cloud Sedna orbit.svg
Oort cloud Sedna orbit.svg
File:Proton-proton reaction chain.svg
Proton-proton reaction chain.svg
File:Evolution of the Sun 2 EN.svg
Evolution of the Sun 2 EN.svg
File:Sun red giant.svg
Sun red giant.svg
File:Heat Transfer in Stars.svg
Heat Transfer in Stars.svg
File:Stylised atom with three Bohr model orbits and stylised nucleus.svg
Stylised atom with three Bohr model...
File:Milky Way Arms ssc2008-10.svg
Milky Way Arms ssc2008-10.svg
File:Solar system barycenter.svg
Solar system barycenter.svg
File:The Local Interstellar Cloud and neighboring G-cloud complex.svg
The Local Interstellar Cloud and...
File:Sun symbol (bold).svg
Sun symbol (bold).svg
File:Highest resolution photo of Sun (NSF) as of January 20, 2020.jpg
Highest resolution photo of Sun (NSF) as...

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