Outer Layers of the Sun
Dana Desonie, Ph.D.
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Printed: November 12, 2014
AUTHOR
Dana Desonie, Ph.D.
www.ck12.org
C HAPTER
Chapter 1. Outer Layers of the Sun
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Outer Layers of the Sun
• Describe the internal and atmospheric 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 1.1). 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 6,000°C.
The Chromosphere
The chromosphere ( Figure 1.2) 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 4,000°C to about 10,000°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 km.
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FIGURE 1.1
The Sun’s atmosphere contains the photosphere, the chromosphere, and the
corona. This image was taken by NASA’s
Spacelab 2 instruments.
FIGURE 1.2
The chromosphere.
The Corona
The corona ( Figure 1.3) 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.
The movie "Seeing a Star in a New Light" can be seen here: http://sdo.gsfc.nasa.gov/gallery/youtube.php .
Vocabulary
• 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: Visible surface of the Sun.
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Chapter 1. Outer Layers of the Sun
FIGURE 1.3
During a total solar eclipse, the Sun’s corona becomes visible, peeking
out from behind the Moon.
Summary
• 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.
Explore More
Use the resource below to answer the questions that follow.
• The Sun’s Outer Layers at http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html
1.
2.
3.
4.
5.
6.
List the outer layers of the Sun.
What is the Sun made of?
Why doesn’t the Sun have a surface, like Earth does?
What does the chromosphere look like in visible light?
What is unusual about the temperature structure of the chromosphere?
When can the corona best be seen? Why is it seen so well then?
Review
1.
2.
3.
4.
What layer of the Sun do you see during a total solar eclipse?
What are the distinctive characteristics of the photosphere?
What are the distinctive characteristics of the chromosphere?
What is the corona?
References
1. Courtesy of NASA. Layers of the Sun. Public Domain
2. Courtesy of Hinode JAXA/NASA. The chromosphere of the Sun. Public Domain
3. Courtesy of NASA. The Sun’s corona during a total solar eclipse. Public Domain
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