Ch. 28 The SUN

28.1 The Structure of the Sun 3 Parts 1.Core 2.Inner Zones Radiative Zone Convective Zone 3.Atmosphere

The Core Entirely composed of Gas Nuclear Fusion Reactor H + H  He + energy Energy is released as heat and light E = mc 2 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.

Stop for Today

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 (H 2 O) - carbon dioxide (CO 2 ) - ammonia (NH 3 )

Eventually photosynthetic organisms converted the carbon dioxide gas found in the oceans into oxygen. This formed our current atmosphere

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