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Energy in the Sun

The sun is a big ball of superheated gases called plasma. The gases are converted into energy in the sun's core. The energy moves outward through the interior layers, into the sun's atmosphere, and is released into the solar system as heat and light.

Sunspot AR 1520 Seen by Solar Dynamics Observatory
NASA's Solar Dynamics Observatory saw sunspot AR 1520 before the solar flare erupted from it on July 12, 2012.
Credit: NASA/SDO 

Most of the gas — about 72 percent — is hydrogen. Nuclear fusion converts hydrogen into other elements. The sun is also composed of about 26 percent helium and trace amounts of other elements — oxygen, carbon, neon, nitrogen, magnesium, iron and silicon.

These elements are created in the sun's core, which makes up 25 percent of the sun. Gravitational forces create tremendous pressure and temperatures in the core. The temperature of the sun in this layer is about 27 million degrees F (15 million degrees C). Hydrogen atoms are compressed and fuse together, creating helium and a lot of energy. This process is called nuclear fusion. For more details on fusion, go here


The energy, mostly in the form of gamma-ray photons and neutrinos, is carried into the radiative zone. Photons can bounce around in this zone for about a million years. The bouncing around in the radiative zone is called The Random Walk. Scientists think the sun's magnetic field is generated by a magnetic dynamo in this layer.

Sun's Radiative Zone: The Random Walk

 The white line in the diagram shows the path of a single photon on it's "random walk".


The convection zone is the outermost layer of the sun's interior. It extends from about 125,000 miles (200,000 km) deep up to the visible surface or the sun's atmosphere. Temperatures cool in this zone, enough for heavier ions — such as carbon, nitrogen, oxygen, calcium and iron — to hold onto their electrons. This makes the material more opaque and traps heat, causing the plasma to boil or "convect."

The convective motions carry heat quite rapidly to the surface, which is the bottom layer of the sun's atmosphere, or photosphere. This is the layer where the energy is released as sunlight. The light passes through the outer layers of the sun's atmosphere — the chromosphere and the corona — before reaching Earth eight minutes later.

The Convection Zone and Granulation

Direct link to video above:

Astronomers who have studied the composition of the sun have cataloged 67 chemical elements in the sun. There may be more, but in amounts too small for instruments to detect. Here is a table of the 10 most common elements in the sun:

Abundance (pct.
of total number
of atoms)
(pct. of total mass)
Hydrogen91.2        71.0        
Helium8.7        27.1        
Oxygen0.078        0.97        
Carbon0.043        0.40        
Nitrogen0.0088        0.096        
Silicon0.0045        0.099        
Magnesium0.0038        0.076        
Neon0.0035        0.058        
Iron0.030        0.014        
Sulfur0.015        0.040       


 Try this Fusion Interactive It discusses nuclear fusion for energy but has a great interactive to show you how fusion works.

Open the file below to listen to the text read aloud.

Lynée Beck,
Sep 25, 2014, 4:43 PM