Download 14.1 History of the Solar System

14-1 History of Solar
System Study
Wandering Stars
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Greeks called the stars that “wandered”
planets, Greek for wandering star.
Greek Ideas: Earth at the Center
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The Greeks thought
that earth was in the
center, and everything
revolved around it
(Geocentric Model).
Ptolemy thought that
the planets still rotated
around earth, but in
small circles around a
big circle (pg 741).
Copernicus’s Idea: Sun in the Center
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Heliocentric – The sun in the center,
planets revolve around it.
This is correct
Galileo’s Observations
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Noticed moons around Jupiter
Venus goes through similar phases as the
moon
Brahe and Kepler

Discovered that the orbit of planets are
ellipses (ovals)
Inertia and Gravity

Inertia
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Gravity
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Tendency for an object at
rest to stay at rest and an
object in motion to stay in
motion
The more mass, the more
inertia
The force that pulls all
objects together
These two factors keep
the planets in orbit
Astronomical Unit (AU)

Average distance between the earth and the
sun (150,000,000 km)

Mars is 1.52 AU’s from the sun, or 1.52
times farther from the sun than earth.