Section 2 The Sun

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Stars and Galaxies T3
Section 2 The Sun
A. Sun’s layers—energy created in the core moves outward through the radiation zone
and the
convection zone and into the Sun’s atmosphere
B. Sun’s atmosphere
1. Photosphere—lowest layer gives off light and is about 6,000 K
2. Chromosphere is the next layer about 2,000 km above the photosphere
3. Extending millions of km into space, the 2 million K corona releases charged
particles as
solar wind
C. Surface features
1. Sunspots—dark areas cooler than their surroundings
a. Temporary features which come and go over days, weeks, or months
b. Increase and decrease in a 10 to 11 year pattern called solar activity cycle
2. Sunspots are related to intense magnetic fields
a. Magnetic fields may cause prominences—huge, arching gas columns
b. Violent eruptions near a sunspot are called solar flares
3. Bright coronal mass ejections (CMEs) appear as a halo around the Sun when emitted
in the
Earth’s direction
a. Highly charged solar wind particles can disrupt radio signals
b. Near Earth’s polar areas solar wind material can create light called an aurora
D. Sun is mostly average
1. Middle-aged star
2. Typical absolute magnitude with yellow light
3. Unusual—Sun is not part of a multiple star system or cluster
How is the Sun similar to and different from other stars? Similar: typical age, absolute
and color; different: not part of a star system or cluster
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