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9 Cards in this Set
- Front
- Back
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Solar System
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~a collection of planets, moons, and other smaller bodies surrounding an ordinary star that we called the Sun.
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Planetary System
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System of planets surrounding a star.
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Our Solar System is a tiny part....
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of our galaxy, which is a tiny part of the universe.
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Self-gravity
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~holds plants and stars together.
~Gravitational attraction between planets or stars that pulls all the parts towards its center. ~Inward force= structural strength ~Outward force= gas pressure in the star ~Outward force<self-gravity=objects contracts ~Outward force<self-gravity= it expands ~Stable object is = |
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interstellar medium
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opposing forces of self-gravity and internal pressure
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interstellar cloud
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~a relatively dense region of the interstellar medium
~has self-gravity ~internal pressure > self-gravity = expanding ~opposing pressure = hotter gas, hold them together |
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Pressure is proportional to
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both density and temperature
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Molecular clouds
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~densest, coolest clouds
~conditions within them allow hydrogen atoms to combine to form hydrogen molecules ~massive enough, dense enough, and cool enough= self-gravity overwhelms internal pressure and collapses ~the collapse would be quick |
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Turbulence
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~the random motion of pockets of gas within the cloud
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