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.

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

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.

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

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”

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.

Stages of Solar Eclipse

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

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

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

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

Debbie’s sun

Exploring_Space__The_Universe

Video_Quiz__The_Sun__Our_Star_Attraction

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.

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.

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.”

Mars

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