1. The Inner Solar System
• The four inner planets are all
relatively small and dense, and
have rocky surfaces.
• The terrestrial planets are
planets similar in structure to
Earth.
• Mercury, Venus, Earth, and
Mars are called the terrestrial
planets.

2. The Sun
• The sun’s energy is produced in
its central region by the fusion
of hydrogen nuclei into helium
nuclei.
• The sun remains stable because
the inward pull of gravity
balances the outward push of
thermal pressure from nuclear
fusion.
Nuclear_Fusion_Joins_Atoms
Nuclear_Fusion_Creates_New_Elements

3. The Sun’s Interior
• The sun’s interior consists of the
core, the radiation zone, and the
convection zone.
• Core – is the sun’s central region,
where nuclear fusion occurs.
• Radiation Zone – is a region of
compressed gas. Energy is
transferred by the absorption and
reradiation of electromagnetic
waves.
• Convection Zone – The outer
layer of the sun. energy is
transferred outwardly by
convection currents.

4. The Sun’s Atmosphere
• Photosphere – the
innermost layer of the
sun’s atmosphere. It is the
visible surface.
• The photosphere is not a
solid, but it is considered
the surface.
• Astronomers can’t see
through the photosphere.
• The_Photosphere_and_the_Solar_Wind

5. The Sun’s Atmosphere
• Chromosphere – is the
middle layer of the sun’s
atmosphere.
• At high temperatures,
hydrogen emits a reddish
color.
• Chromosphere means
“sphere of color”

6. Corona
• The corona is the
outermost layer of the
sun’s atmosphere.
• The gases are thin at
this layer
• The chromosphere and
corona can only be
seen during solar
eclipses.

7. Stages of Solar Eclipse
• The corona can only
be seen from Earth
during a total solar
eclipse or when
viewed with a special
telescope.

8. Features of the Sun’s
Atmosphere
• Sunspots – small dark
regions on the sun’s
surface.
• Sunspots are areas of
gas in the photosphere
that are cooler than the
surrounding gases.
• Sunspots give off less
energy

9. Other Features
• Prominences – occur near sunspots. They
are huge loops of gas that erupts.
• Solar Flares – the sun’s surface erupts
hurling charged particles into space

10. Review Concepts
• What is the source of the sun’s energy?
• Nuclear fusion in the sun’s core.
• What two forces in the sun interact to produce a stable structure?
• Gravity and the thermal pressure from fusion.
• List the layers of the sun’s interior from the center outward and
describe each one.
• Core: central region where fusion takes place; Radiation zone: middle
layer, energy is transferred by radiation;
convection zone: outer layer, energy is transferred by convection.
• List the layers of the sun’s atmosphere
• Photosphere, chromosphere, corona
• List three features that exist on the sun’s surface.
•Sunspots, Prominences, and Solar flares

11. Debbie’s sun
Exploring_Space__The_Universe
Video_Quiz__The_Sun__Our_Star_Attraction

12. Mercury
• Mercury is the smallest of the
terrestrial planets and the
closest planet to the sun.
• Mercury is a dense planet with
a very large iron core.
• Mercury is geologically dead.
• There is no mantle convection
within the planet and little
erosion on its surface.

13. Venus
• Venus’s thick atmosphere is
composed mostly of carbon
dioxide, which traps heat and
raises the planet’s temperature.
• Venus’s atmosphere contains
droplets of sulfuric acid.
• Average surface temperature
460 degrees.

15. Mars
• Mars is the most Earthlike of all of the
planets. The weathering of iron rock on its
surface gives the planet a reddish color.
This is why Mars is called the “Red Planet.”

16. Mars

17. Asteroids
• Beyond Mars is a region of
small, rocky bodies called
asteroids that orbit the sun.
• This region is referred as the
asteroid belt
• Scientist now hypothesize that
asteroids are remnants of the
early solar system that never
came together to form a planet