Transcript Origins of the Universe

Origins of the
Universe
The Greeks
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Ptolemy and Aristotle
Planets were believed to be perfect
spheres and orbits were circles
Earth was the centre of the universe
They could track the motions of the sun,
moon, Mercury, Venus, Jupiter, Mars, and
Saturn
Geocentric View of Universe
Ptolemy & Aristotle
Ptolemy & Aristotle
“GEO” = Earth
“Centric” = center
Problems with the geocentric model:
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Retrograde
motion:
during certain
times of the
year Mars,
Jupiter and
Saturn
appeared to
be moving
backwards
Problems with the geocentric model
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Ptolemy explained this with epicycles –
planets went in little circles as they orbited.
Heliocentric View of Universe
Copernicus
“HELIO” = Sun
“Centric” = center
Orbits are still circles
The Heliocentric Model
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Provided a simpler way to explain
retrograde motion
Galileo
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Further added support to the heliocentric
model when he made his first observations
with a telescope
Galileo was able to observe
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craters on the moon
Sun spots that changed over time
suggesting the rotation of the Sun
Moons that orbited around Jupiter (which
also contradicted the geocentric model)
Stars were farther away than planets
Kepler
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Used careful measurements and star
charts recorded by Tycho Brahe
His calculations showed that the planetary
orbits were elliptical (NOT circular)
So why did the planets orbit in
ellipses, not circles?
Newton
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Law of Universal Gravitation – there is a
force between all objects that pulls them
together
Larger objects have more gravity
Gravity explained why the planets moved in
elliptical orbits – further supporting the
heliocentric model.
Exploring Elliptical Orbits Activity
• Kepler –
established that
the planets moved
around the sun in
elliptical orbits.
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Edwin Hubble observed that the galaxies
were moving away from each other
He predicted there was a time when all
matter was together
These observations led to the BIG BANG
THEORY
Our Solar System
INNER/TERRESTRIAL
PLANETS
OUTER/GASEOUS/JOVIAN
PLANETS
Planets
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Are different based on:
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Size
Motion
Composition
Density
Surface temperature