Ch. 28 The SUN

28.1 The Structure of the Sun

3 Parts1.Core2.Inner Zones

Radiative ZoneConvective Zone

3.Atmosphere

The Core

• Entirely composed of Gas• Nuclear Fusion Reactor

H + H He + energy

• Energy is released as heat and light

E = mc2

Energy = (mass)(speed of light)2

The Inner Zones

• Radiative Zone: Energy is moving from atom to atom in the form of waves (radiation)

• Convective Zone: Energy is transferred through the movement of unevenly heated gases (convection)

The Sun’s Atmosphere

• Photosphere: Inner most layer• Chromosphere: gasses that appear to glow

red• Corona: The outermost layer– Solar Wind: Charged atomic particles that stream

out into space

Solar Activity

• Sun Spots: Cooler gases that appear dark in comparison to surrounding gasses.

• Prominences: clouds of gasses that arch into space.

• Solar Flares: outward eruption of electrically charged particles.

• Auroras: When electrically charged particles of a solar wind reach earth.

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28.3 Formation of the Solar System

1. About 4-5 billion years ago, a Solar Nebula contracted due to an outside force.

2. The Sun began to form at the center of the contacting nebula – 99% of the matter in the nebula became the sun

3. Left over matter aggregated to form the planets

• Temperature and Distance from the Sun affected the planetary composition. – Proto-planets closest to the sun contain large

amounts of heavier elements, such as iron– Proto-planets further away consist of gasses and

lighter elements

Formation of Earth• Early Earth was very hot compared to Earth

today. – Heat from collisions with plantesimals– Increasing mass of the outer core, increased inner

pressure and temperature– Radioactive materials were very abundant

Separation into 3 layers

• Dense materials, such as iron, flowed into the center

• Less dense materials were forced to the outer layers

Formation of the Atmosphere

• Original atmosphere just hydrogen and helium

Earth’s “second atmosphere” came from Earth itself.

The volcanoes released:- steam (H2O)- carbon dioxide (CO2)- ammonia (NH3)

Eventually photosynthetic organisms converted the carbon dioxide gas found in the oceans into

oxygen. This formed our current atmosphere

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