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