Transcript 3OriginofPlanetsandMoons

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Origins of the Planets
and Moons
Remember from before…
VI. Formation of OUR solar system:
•Our sun was the center of a nebula (cloud of
dust and gas).
•Planets formed when bits of matter first
collided and aggregated into small, irregular
shapes (planetesimals), and eventually
formed into larger planets.
•As the planets formed, the more dense ones
were pulled closest to the sun. They are
called Terrestrial Planets (Mercury, Venus,
Earth, and Mars).
•The less dense planets moved toward the
outer portion of the solar system. They are
called Jovian Planets, or Gas Giants. (Jupiter,
Saturn, Uranus, and Neptune)
•Pluto is now thought to be a minor planet,
most likely a captured comet who was drawn
in by the gravity of the sun and placed in an
orbit around it (similar to asteroids)
VII. Planetary Development
Terrestrial planets (like Earth) go through the
same 4 stages of development:
1. DIFFERENTIATION - heavier materials
move to the center of the planet, lighter
materials move to the outer portion while it is
still molten (liquid)
2. BOMBARDMENT - planets receive surface
features due to cratering from space debris
(there was much more debris in the early
universe!)
3. FLOODING - planets were covered with
molten rock or water, filling in lower areas
4. SURFACE EVOLUTION - planets continue
to change their look from impacts, erosion, or
plate tectonics.
Jovian planets (gas giants) all went through
differentiation, but we are unsure about
development after that. We DO know that they
are constantly influenced by storms that move
through their thick atmospheres.
VIII. Formation of moons and rings
Planets have moons for 2 different reasons:
•A large object in space hit the planet, throwing out
debris that collected into a moon (ex: Earth’s
moon)
•Asteroids have been captured by the planet when
the came too close, getting trapped by the
gravitational pull of the planet (ex: the moons of
Mars)
All planets have moons except Mercury and Venus
Some planets also have rings:
•Ring are either debris blown away from the planet
but trapped in it’s gravitational field OR they are
rings of debris from captured space debris.
•Only the Gas Giants have rings
IX. Life
Earth is special in the universe, because it is the only place that we know of
when life has evolved; where chemistry (water and chemicals) and physics
(energy) have created biology…
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