• 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.

• 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

• 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.

• 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_t he_Solar_Wind

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

• 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.

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

• 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

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

• 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

Exploring_Space__The_Universe
Video_Quiz__The_Sun
__Our_Star_Attraction

• 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.

• 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.

• 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.”

• 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