Download Chapter 8 lesson 4 Notes

Chapter 8 Lesson 4- Stars and the Universe
Vocabulary
1. Star
2. Nebula
3. White dwarf
4. Supernova
5. Black hole
6. Constellation
7. Light-year
8. Galaxy
NOTES
How do stars form?
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Stars form when matter comes together and starts to give off energy.
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Stars go through stages and different stars go through different stages.
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The cycle of a star depends on how much hydrogen the star contains.
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A stars cycle ends when it stops giving off energy.
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All stars form from a nebula.
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Gravity pulls the mass off the nebula together.
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As they get closer together they collide with each other.
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Collisions produce heat and the temperature to rise.
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Protostar – beginning star.
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Hydrogen is the fuel that produces energy in the sun.
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Red giant many times larger than a normal star.
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Helium atoms started forming carbon.
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Eventually the helium begins to cool down and can’t make carbon.
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The star shrinks and becomes a white dwarf.
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This is the end of the medium sized star cycle.
What happens to larger stars?
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Supernovas shine brightly for days or weeks and then fade away.
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A supernova will form a new nebula.
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Stars are characterized by their color and temperature.
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Red and Orange= cooler
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Giant stars have diameters that are 10 to 100 times of the sun.
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Giant Stars-10-100
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Super Giants-1000
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Neutron stars- smallest
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Gravitational Microlensing- analyzing data of the stars brightness for changes that
Yellow=Middle
White and Blue=Hotter
show that a planet passed in front of a star.
What are constellations?
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Constellations are named after animals, characters in stories, and familiar objects.
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Constellations help us with directions.
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Polaris-north star
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If you are lost in the woods, look for Polaris it will guide you to safety.
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Next closest star to earth is Proxima Centauri, 40 trillion, 4.2 light years, away.
What are star systems?
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Each galaxy holds millions of stars.
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The basic shapes are spiral, elliptical, and irregular.
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Our solar system is located in the Milky Way galaxy.
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The Milky Way is a spiral galaxy.
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Bared spirals galaxies have 2 arms that spread across.
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Elliptical galaxies are round and look like a think pancake.
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Irregular galaxies have no definite shape.
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Clusters are shaped like a sphere and hold a 100,000 or more stars.
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Binary stars- when 2 stars form near each other and around each other.
How did the universe form?
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The Big Bang Theory- the universe started out as a big bang and has been
expanding ever since.