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Outer Layers of the Sun

Heat moves through the outer layers of the Sun.

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15.3 Outer Layers of the Sun

What can you see during a solar eclipse?

A solar eclipse is kind of like a field trip to the Sun from Earth. You can see something (with special tinted glasses) that you don't usually see. The Sun has a remarkable ring of light around it. This is the corona. If you have a chance to see a solar eclipse you should do it.

The Outer Layers

The three outer layers of the Sun are its atmosphere. The layers are, from inside to outside, the photosphere, the chromosphere and the corona.

The Photosphere

The photosphere is the visible surface of the Sun (Figure below). It's the part that we see shining. Surprisingly, the photosphere is also one of the coolest layers of the Sun. It is only about 6000 degrees C.

The Sun's atmosphere contains the photosphere, the chromosphere, and the corona. This image was taken by NASA's Spacelab 2 instruments.

The Chromosphere

The chromosphere lies above the photosphere. It is about 2,000 km thick. The thin chromosphere is heated by energy from the photosphere. Temperatures range from about 4000 degrees C to about 10,000 degrees C. The chromosphere is not as hot as other parts of the Sun, and it glows red. Jets of gas sometimes fly up through the chromosphere. With speeds up to 72,000 km per hour, the jets can fly as high as 10,000 kilometers. You can see an image of the chromosphere in the Figure below.

The chromosphere.

The Corona

The corona is the outermost part of the Sun's atmosphere. It is the Sun’s halo, or “crown.” With a temperature of 1 to 3 million K, the corona is much hotter than the photosphere. The corona extends millions of kilometers into space. Sometime you should try to see a total solar eclipse. If you do you will see the Sun’s corona shining out into space, like in the Figure below.

The Sun has been blocked in order to see the corona

The movie "Seeing a Star in a New Light" can be seen here: http://sdo.gsfc.nasa.gov/gallery/youtube.php.


  • chromosphere: Thin layer of the Sun’s atmosphere that lies directly above the photosphere. This layer glows red.
  • corona: Outermost layer of the Sun. A plasma that extends into space.
  • photosphere: The visible surface of the Sun.


  • The photosphere is the part of the Sun that we see shining.
  • The chromosphere is an active layer that glows red.
  • The corona is the halo around the Sun.


Use this resource to answer the questions that follow.


  1. List the outer layers of the sun.
  2. What is the temperature of the photosphere?
  3. What is the chromosphere?
  4. What is the temperature of the chromosphere?
  5. When can the corona be seen?


  1. What layer of the Sun do you see during a total solar eclipse?
  2. Which layers of the Sun give it which distinctive characteristics?
  3. What is the corona?

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