Transcript Chapter 28 Notes

Chapter 28 Notes
Our Solar System
Our Solar System
The Inner Planets (and Pluto)
All the Planets (and Pluto)
The Planets and the Sun (and Pluto)
Formation of the Solar System
• Nebular Theory:
a) Interstellar cloud
contracts and spins
b) Dense center begins
nuclear fusion (sun)
c) Remaining material
forms planetesimals
and then planets
Historical Solar System Models
• Geocentric (Earth-centered)
model
– One problem was how to explain
retrograde motion
• Copernicus’ heliocentric model
– 1543, Polish scientist
– Planets (including Earth) orbit the
Sun in circular orbits
– Supporting evidence collected by
Tycho Brahe
Kepler’s laws of planetary motion
• Johannes Kepler inherited Tycho’s data after
his unexpected death.
Galileo
• First person to use a telescope to observe the
sky
• Discovered moons orbiting Jupiter
• Also observed sun spots, phases of Venus, and
Moon craters
Newton and Gravity
• Newton’s discovery of the law of universal
gravitation provided an explanation for the
heliocentric model of the solar system
Zone 1: Inner Planets
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Terrestrial: “Earth-like”
Small
Composed of rock (high density)
Close to the Sun
Few or no moons
No rings
Mercury
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Smallest
Closest to the Sun
No moons
No atmosphere
Cratered like the Moon
1 orbit = 1.5 rotations (2 years = 3 days)
Venus
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No moons
Earth’s “twin” in size
Rotates backwards
1 day = 243 Earth days
Very high CO2 concentration in the atmosphere
causes super greenhouse effect
• Surface temperature of 464C!!
• Can be seen as a bright morning or evening “star”
Earth
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One moon
Tectonically active
O2 in atmosphere
Water exists in all 3 phases
Mild greenhouse effect to
keep the planet warm
enough for life
Mars
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The red planet
CO2 atmosphere
2 moons (Phobos and Deimos)
Has seasons like Earth, but a year is twice as
long
• Largest volcano in the solar system: Olympus
Mons
• Once had liquid water, has polar CO2 ice caps
Outer Planets
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Gas giants or “Jovian”: Jupiter-like
Large
Low density
Lots of moons
All have ring systems
Far from the Sun
Jupiter
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Largest planet
Banded appearance
Great red spot
Faint ring system
4 large moons, more than 60 total
Rapid rotation (10 hours = 1 day); shortest day
of all the planets
Saturn
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Famous for ring system
More than 55 moons
Density lower than water
Largest moon, Titan, has an atmosphere of
nitrogen and methane
• Another moon, Enceladus, shows evidence of
geologic activity
Uranus
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Discovered in 1781
Rotational axis is 98
At least 27 moons
Rings are dark and nearly
invisible
• Appears blue because of
the way it reflects light
Neptune
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Discovered 1846
13 moons
Distinctive clouds and belts
Predicted before it was discovered
6 rings composed of dust particles
Largest moon, Triton, orbits backwards
Other Solar System Objects
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Dwarf planets
Asteroids
Kuiper belt objects (KBOs)
Comets (the Oort cloud)