november 19, 2012 sanders 8-11 stars unit 8: astronomy
TRANSCRIPT
November 19, 2012November 19, 2012 SandersSanders
8-11 Stars8-11 Stars
Unit 8: AstronomyUnit 8: Astronomy
Astronomy
Stars’ Classification
• Stars are classified by temperature and luminosity.– Temperature can be seen by the color of
the star.• A red star is coolest• A blue star is hottest
– Luminosity is the rate at which the star emits energy compared to the sun.
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Astronomy
Changing Knowledge
• People have observed the stars for thousands of years, using them to find direction, note the passage of time, and to express their values and traditions.
Astronomy
Changing Knowledge
• People have observed the stars for thousands of years, using them to find direction, note the passage of time, and to express their values and traditions.
• As our technology has progressed, so has understanding of celestial objects and events.
Astronomy
Nuclear Fusion
• Fusion releases great amounts of energy over millions of years.
Astronomy
Nuclear Fusion
• Fusion releases great amounts of energy over millions of years.
• Hydrogen is fused to make helium.
Astronomy
Nuclear Fusion
• Fusion releases great amounts of energy over millions of years.
• Hydrogen is fused to make helium.
• When hydrogen is consumed, more and larger elements are consumed.
Astronomy
Fusion
Astronomy
Milky Way• Our Sun is a medium-sized star within a spiral
galaxy of stars known as the Milky Way.
Astronomy
Milky Way• Our Sun is a medium-sized star within a spiral
galaxy of stars known as the Milky Way.
• Our galaxy contains billions of stars, and the universe contains billions of such galaxies.
Astronomy
Stars Life Cycle• Stars have a life cycle.
Astronomy
Stars Life Cycle• Stars have a life cycle.• The first stage in a star's life cycle
is a protostar.
Astronomy
Main Sequence• The second stage in a star's life cycle is
the main sequence stage.
Astronomy
Main Sequence• The second stage in a star's life cycle is
the main sequence stage.• A medium-sized star becomes first a
white dwarf and then a black dwarf.
Astronomy
Main Sequence• The second stage in a star's life cycle is
the main sequence stage.• A medium-sized star becomes first a
white dwarf and then a black dwarf.
Astronomy
The Rosette Nebula • Stars form when
gravity causes clouds of molecules to contract until nuclear fusion of light elements into heavier ones occurs.
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Ring Nebula Deep Field Ring Nebula Deep Field
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Young Stars in the Rho Ophiuchi Cloud
Young Stars in the Rho Ophiuchi Cloud
Astronomy
Stars Young and Old Stars Young and Old
Astronomy
Crab Pulsar Wind Nebula Crab Pulsar Wind Nebula
Astronomy
The Crab Nebula from Hubble
The Crab Nebula from Hubble