2. 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.

3. 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

4. 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.

5. 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_t he_Solar_WindThe_Photosphere_and_t he_Solar_Wind

6. 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”

7. 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.

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

9. 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

10. 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

11. 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

12. Debbie’s sun Exploring_Space__The_Universe Video_Quiz__The_Sun __Our_Star_Attraction

13. 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.

14. 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.

16. 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.”

17. Mars

18. 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