Download The Sun is our local star.

KEY CONCEPT
The Sun is our local star.
STANDARDS
8–4.2 Summarize the
characteristics of
the surface features of
the Sun: photosphere,
corona, sunspots,
prominences, and
solar flares.
8–4.3 Explain how the
surface features of the
Sun may affect Earth.
BEFORE, you learned
NOW, you will learn
• There are different wavelengths
of electromagnetic radiation
• The Sun provides light in
the solar system
• How the Sun produces energy
• How energy flows through the
Sun’s layers
• About solar features and
solar wind
EXPLORE Solar Atmosphere
How can blocking light reveal dim features?
MATERIALS
PROCEDURE
1
Unbend the paper clip and use it to make
a tiny hole in the center of the card.
2 Turn on the lamp, and briefly try to read
VOCABULARY
fusion p. 692
convection p. 692
corona p. 692
sunspot p. 694
solar wind p. 695
• small paper clip
• index card
• lamp with
45-watt bulb
the writing on the bulb.
3 Close one eye, and hold the card in
front of your other eye. Through the hole,
try to read the writing on the bulb.
WHAT DO YOU THINK?
• How did looking through the hole affect
your view of the writing?
• How might a solar eclipse affect your
view of the Sun’s dim outermost layer?
The Sun produces energy from hydrogen.
MAIN IDEA AND DETAILS
You could record information about the Sun by
using a main idea and
details table.
The Sun is the only star in our solar system. Astronomers have been
able to study the Sun in more detail than other stars because it is much
closer to Earth. As a result, they have learned a great deal about its size
and composition and the way it produces energy.
The Sun is far larger than any of the planets. It contains 99.9 percent
of the mass of the entire solar system. For comparison, imagine that
Earth had the mass of a sparrow; then the Sun would have the mass of
an elephant.
The Sun consists mostly of hydrogen gas. Energy is produced when
hydrogen in the Sun’s interior turns into helium. This energy is the
source of light and warmth that make life possible on Earth.
Chapter 20: Stars, Galaxies, and the Universe 691