Download Chapter 3: Our Solar System Intro to Our Solar System

Chapter 3: Our Solar
System
Intro to Our Solar System
Our Solar System
• Most of the planets in our solar system can be
seen without a telescope.
• Uranus and Neptune are the only two too far to
see.
• The largest planet is about 10 times larger than
Earth across.
Our Solar System
Distances
• Astronomers use astronomical units, or AUs, to
measure distance in space.
• 1 AU = distance from Sun to Earth; about 150
million km.
• The first four (inner) planets are relatively close to
one another; the outer planets are much more
spaced out.
Orbits
• More than 99% of the Mass in our Solar
System is the Sun.
• This results in a strong gravitational pull on
everything else.
• Each planet (and other objects) orbits the Sun
in an elliptical, or oval, shape.
Orbits
• All planets orbit in the same direction, and most
other objects do, also.
• Scientists think this is a clue – the solar system
formed from a huge cloud of gases and dust; most
mass = Sun, the rest clumped together to form
planets.
• Not all of them were large enough to planets;
resulting in asteroids, comets, and moons.
Chapter 3: Our Solar
System
The Inner Planets
Inner Planets
• Mercury, Venus, Earth, and Mars
• Called terrestrial planets
• Rocky crust, dense mantles and cores
Processes and Surface
Features
• They all have layers; the heaviest materials sank to
the center in their collisions and the lightest rose
to become crust.
• Four main processes shaped the crust:
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Tectonics
Volcanism
Weathering and erosion
Impact cratering
Tectonics
• Earth’s crust has tectonic plates that are moved by
convection in the mantle.
• As the plates move, different features (mountains,
valleys) are formed.
• The other planets do not have plates, but still are able
to move with the mantle.
• Tectonics: process of change in the crust due to
motion of material in the mantle.
Volcanism
• Occurs when molten rock moves from the
interior to the surface.
• Volcanoes are on Earth, Venus, and Mars.
• When the inside of a planet cools enough, no
more molten rock reaches the surface.
Weathering and Erosion
• Water and wind are important factors on Earth.
• Planets without wind still have weathering due
to heating and cooling of the surface.
Impact Cratering
• When small objects hit a larger object and
leave a resulting indentation.
• Harder to find on Earth
• Easily found on other planets due to less
weathering/erosion.
Atmospheres
• Mainly formed from volcanic gases.
• Venus, Earth, and Mars have enough gravity to
hold in gases like CO2, but lighter gases
escaped.
• Earth is mostly nitrogen.
• Can make a planet warmer due to loss of
energy
Mercury
• Believed to shrink from original size, creating
cliffs.
• Large areas of cooled lava.
• Several impact craters, suggesting the surface
has not changed much.
• Longest cycle of day and night – 3 months of
daylight, 3 months of darkness.
• Can get 800+ F during day, and -170 F during
night.
Mercury
Venus
• Slightly smaller than Earth.
• 8 months to turn once; retrograde rotation
(opposite way than orbit) creates 2 months of
daylight and 2 months of darkness.
• Very dense, mostly CO2.
• Temp = about 470 F.
• Sulfuric acid in atmosphere form thick clouds.
Mars
• About half the size of Earth
• Two moons – Deimos and Phobos
• Red because of iron/rust
• Large valley – Valles Marineris
• Large areas of cooled lava; several volcanoes
• Winds up to 300 mph; sand dunes.
• Several craters
Mars
• Mostly CO2 in atmosphere, but very low air
pressure.
• Temps vary from about 60 F in day to -130 F at
night.
• Polar caps, mostly made of dry ice.
• No liquid water on surface, but there is frozen
water in ground.
Chapter 3: Our Solar
System
The Outer Planets
Outer Planets
• Jupiter, Saturn, Uranus, and Neptune – gas
giants : mostly made of H, He, and other gases.
• The atmosphere is very thick, almost like a
liquid in some places.
• They are all believed to have a large, solid core.
Jupiter
• Largest planet
• 5.2 AU from Sun
• 1 year = 12 Earth years
• Fast rotation = fast wind and storms
• White clouds made of ammonia; lower clouds
are brown/red and made of chemicals
• Storms form between winds; the largest is the
Great Red Spot (100+ years old).
Saturn
• Gas particles spread out more, forming layers
of clouds.
• Rings: wide, flat zone of small particles that
orbit a planet.
• Bright rings made out of water ice chunks, with
moons mixed in.
• Axis is tilted at 27 degrees; rings appear to
change b/c of this.
• 1 year = almost 30 Earth years.
Uranus and Neptune
• Mostly methane, ammonia, and water.
• Uranus = blue/green; Neptune = dark blue –
colors are from methane.
Uranus
• 1 year = 84 Earth years
• Rings and moons around equator
• Seems to spin on its side
• Scientists think the unusual rotation was
caused from a collision.
Neptune
• Sometimes looks white due to methane clouds
• Severe storms, such as the Great Dark Spot,
can be seen in darker shades of blue.
• This storm moved toward the equator, where it
is thought that the winds broke up the storm.
Chapter 3: Our Solar
System
Other Objects
Pluto
• Was once a planet.
• Discovered in 1930
• No spacecraft has been close to it.
• Has a moon, Charon – they orbit each other;
sometimes called a “double planet”.
• More oval-shaped orbit
• 1 year = 248 Earth years
Asteroids
• Small, solid, rocky bodies that orbit close to Sun.
• Most have irregular shapes
• Most between Mars and Jupiter – The Asteroid Belt
• Craters, broken rock, and dust cover them; most
have no atmosphere and no layers, so surfaces
don’t change.
• Can hit Earth – 65 mya, a 6 mi asteroid hit Earth
and sent dust into the air, most likely changing the
temps of Earth and killing off any living organisms.
Comets
• Have oval orbits
• Have a coma (cloud of material) and a tail (gets
longer closer to the Sun).
• Small, icy rock is hard to see without the parts
above.
• The tail always points away from the Sun.
• Halley’s Comet – orbits approx. every 75 years;
expected to return in 2061.
Meteors & Meteorites
• Meteors: Brief streaks of light caused by hot
particles/air in the upper atmosphere.
• Usually can see a few/hour in the night sky.
• Usually very quick, only a few seconds.
• Meteorites: space object that reaches Earth’s
surface
• Usually smooth on the outside from melting; inside
can still be icy.