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22 terms

ASTR103 - Solar system formation

Week 4 topics
STUDY
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Evolutionary hypothesis
Descartes proposed that the solar system formed from a contracting vortex of matter.
Catastrophic hypothesis
Buffon later suggested that a passing comet pulled matter out of the sun to form the planet
Passing star hypothesis
Astronomers replaced the comet with a star from catastrophic (comet) hypothesis
Nebular hypothesis
Laplace's hypothesis required a contracting nebula to leave behind rings that formed each planet
Angular momentum problem
Puzzle of the sun's low angular momentum
Solar nebula theory
Theory proposes that the planets formed in a disk of gas and dust around the protostar that became the sun
Terrestrial planets
Inner four planets, small, rocky, dense
4 terrestrial planet
Mercury
Venus
Earth
Mars
Jovian planets
Outer planets, large, low density
4 jovian planets
Jupiter
Saturn
Uranus
Neptune
Asteroids
Small, irregular, rocky bodies, are located between the orbits of Mars and Jupiter
Kuiper belt
Small, icy bodies that orbit the sun beyond the orbit of neptune
Comets
Icy bodies that pass through the inner solar system along long elliptical orbits. As the ices vaporize and release dust, the comet develops a tail that points approximately away from the sun
Meteoroids
Rock in space in space before it plunges into the Earth's atmosphere
Meteors
Small bits of rock and metal colliding with Earth's atmosphere and bursting into incandescent vapor because of friction with the air about 80 km above the ground. Commonly called "shooting stars".
Meteorites
Specks of dust, grains of sand, or tiny pebbles that survive the passage to Earth's surface.
Half-life
the age of a rocky body found by radioactive dating based on decay
Condensation
During the solar nebula converted some of the gas into solid bits of matter
Accretion
Bits of matter from condensation grow by this process
Planetesimals
Accretion bits of matter form billions of these
Protoplanets
Planets begin growing by accretion of solid material into this
Gravitational collapse
Once a protoplanet approaches about 15 Earth masses, it can begin growing by this process by pulling gas from the solar nebula