Transcript The Solar System

Chapter 13
The Solar System
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 “They
conveniently forget that
long ago all the galaxies and
this very planet were brought
into existence out of watery
chaos by God’s word.”
2 Peter 3:5
Planets, moons and other
bodies

Our Solar System
 Sun
 8 planets ?
 ~100 moons
 Thousands of asteroids, millions of
icy bodies, comets, …
Planets, moons and other bodies

Astronomical unit (AU)
Average Earth-Sun distance
 1.5x108 km
 1 km = 0.621 mile or 3280.8 feet
 @ 93 million miles

 (92,900,836.17

mi or 149,589,777 km)
Light –year (lt-yr) is used for longer distances
 How
far light travels in one solar year
 Speed of light = 186,282,3976 miles per second
 5,880,000,000,000mi or 63,240 AUs !!!

Planet classification:
size
 density
 atmosphere


Two main divisions
Inner Planets
 Outer Planets

Inner Planets
 1.
FourTerrestrial planets - mostly
rocky material, metallic nickel and
iron
Mercury
Venus
Earth
Mars
Outer Planets

2. Four Giant Gas Planets - mostly
hydrogen, helium and methane
Jupiter
Saturn
Uranus
Neptune
Pluto
is now considered a dwarf
planet
The order of the planets
Mercury


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Innermost planet
2,439.7 km radius
Highly elliptical orbit
Average distance from
Sun~ 0.4 AU (36 million
miles)
Orbital period (year) ~
88 days
Sun rise to sun rise
(“day”) ~ 176 days
Mercury
Visible shortly
after sunset or
before sunrise
No atmosphere;
No moons
40% smaller than Earth
 Day hot enough to melt metal 427 C
 Night cold as liquid nitrogen -173 C
 Mariner 10 flew past Mercury in 1974
 Magnetic field
 Craters like our moon
 Cliffs hundreds of kilometers high and long
 Plains of smooth lava

Venus
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Orbital distance from
Sun ~ 0.7 AU (67
Million miles)
Morning and evening
“star”
Exhibits phases, like
the Moon
No moons
Rotational motion
opposite orbital
motion
Venus

Venusian “day” longer than Venusian
“year”
Day is 243 Earth days
 Year is 224.7 Earth days

Visited by numerous probes
 Mostly CO2 atmosphere, high temperature
and pressure
 Surface mostly flat but varied

Venus
 3rd
brightest in
sky
 Called the sister
planet of earth
 nearly same
size and
weight
Venus

Actually hotter than Mercury (900O F)

“Greenhouse” effect
Clouds of sulfur and CO2
 462 C surface temperature
 Besides “morning star” known as:

“witch star”
 “dragon star”

“nearest you can get to hell”
(Russian Probe lasted less than an hour)
Venus
Earth’s Moon

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
1/6th gravity of earth
no atmosphere
one orbit takes 27
days
238,857 miles from
earth
never see dark side
12 Apollo astronauts
have walked on the
moon (1969-1972)
footsteps still there

"That's one small step for man," "One giant leap for
mankind.“Neal Armstrong July 20, 1999
Earth’s Moon

Lunar highlands
Light colored
mountainous
regions
 craters
 Breccias - rock
fragments
compacted from
meteorite impact

Earth’s Moon

Maria (“sea”)
Smooth dark areas formed from floods of
lava
 Basalt - similar to rock formed from cooling
lava on earth
 Formed about 3.1 – 3.8 billion years ago


Surface

3 meters grey dust containing microscopic
glass beads formed by bombardment of
meteorites
Moon Rocks


Glass
840 pounds brought
back
Lunar Eclipse
Mars – the Red Planet
Mars

Orbital distance from
Sun~ 1.5 AU (141 million
mi)

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One year is 687 days
One day is 24 hrs and
37 minutes
½ the size of earth
Numerous space
probes
2 moons


Deimos
Phobos
Mar’s Moons
Mars
 Inactive
volcanoes
Canyons
 Terraced plateaus
 Flat regions pitted
with craters
Mars

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Thin atmosphere,
95% CO2--freezes
at the south pole
Strong evidence for
liquid water in past
Olympus Mons is
16 miles high
(Everest is 5 ½
miles high)
dust storms
http://mars.nasa.gov/programmissi
ons/missions/log/
Spirit and Opportunity
Mars Exploration Rovers


Found that Mars
made of basalt
rock and
groundwater that is
dilute sulfuric acid
Confirmed
sufficient amounts
of water have been
present in the past
Spirit Rover
ExoMars
2015
http://www.space.com/18027mars-rover-curiosity-amazingphotos-red-planet.html
Earth
and
Moon
from
Mars
Jupiter
Jupiter

~ 5 AU from Sun

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One orbit is 12 EY
Day is 10 hours
Most massive planet


483 million miles
318 times Earth’s
mass
200 pound man
would weigh 500
pounds
Jupiter
4th brightest object
in sky
 Mostly H, He &
iron-silicate core
 “Dynamic”
atmosphere



H2, He, ammonia,
methane, water,
Rings are present
Jupiter

Great Red Spot
permanent
“hurricane”
 2-3 Earths
could fit inside
spot

Jupiter’s Moons
39 widely varying
satellites (moons)
 Galilean moons:
 Io (active
volcanos)
 Europa
 Ganymede
 Callisto

1994 Shoemaker-Levy Comet
hits Jupiter
Saturn
Saturn

9.5 AU from Sun


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
886.2 million miles
10 hr day
29 1/2 years to orbit Sun
Second largest planet
10 times larger than earth
Many rings made of ice
and rocks
Mainly hydrogen and
helium
Surface similar to Jupiter’s
 Very cold -285 F
 Surface has dark and light bands
 Rapid Rotation causes the equator to
bulge
 Lowest Density = 0.7 that of water (float)

Saturn

30 satellites
 Titan: Largest
(Mercury) only
moon in solar
system with
substantial
atmosphere
(nitrogen)
Uranus
Uranus
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Uranus (~19 AU)
3rd largest planet
84 year orbit
16 hour day
27 moons
Rings present
1/400th sunlight earth
receives
Uranus’ Five Major Satellites
Neptune

Neptune: Blue Planet
(~30 AU) 3 billion km
165 years to orbit Sun
Great Dark Spot

Turbulent atmosphere

Very cold surface of
frozen hydrogen and
helium

13 moons

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
Triton largest moon
Pluto
Pluto:
Smaller than the
Moon
70% rock; 30%
water ice;
thin atmosphere
Unusual orbit
Tilted 17o from
ecliptic
Crosses
Neptune’s
Smaller bodies of the Solar System
Comets, asteroids,
meteorites
 Leftover from solar
and planetary
formation
 Mass of smaller
bodies may be 2/3
of total Solar
System mass
 Bombard larger
objects

Comet structure


Small, solid
objects
“Dirty snowball”
model
 Frozen water,
CO2, ammonia,
and methane
 Dusty and rocky
bits
Comet structure

Comet head


Solid nucleus and coma of gas
Two types of tails
1. Ionized
gases
2. Dust

Tail points away from Sun
Asteroids


Located in belt
between Mars and
Jupiter
Sizes: up to 1,000 km
Asteroids

Varied composition
Inner belt: stony
 Outer belt: dark with carbon
 Others: iron and nickel

Formed from original solar nebula
 Prevented from clumping by Jupiter
nearby

Meteors and meteorites

Meteoroids
 Remnants
of
comets and
asteroids
Meteors and meteorites
Meteor
 Meteoroid encountering Earth’s
atmosphere
 Meteor showers: Earth passing through
comet’s tail
 Meteorite
 Meteoroid surviving to strike Earth’s
surface

Origin of the Solar System
Protoplanet nebular
model
 Stage A


Formation of heavy
elements in many
earlier stars and
supernovas
Concentration in one
region of space as
dust, gas and
chemical compounds
Origin of the Solar System

Stage B
 Formation of large,
rotating nebula
 Gravitational
contraction, spin
rate increases
Origin of the Solar System

Most mass concentrates in central protostar

Remaining material forms accretion disk

Material in accretion disk begins clumping
Origin of the Solar System

Stage C


Solar ignition flare-up
may have blown away
hydrogen and helium
atmospheres of inner
planets
Protosun becomes a
star
Origin of the Solar System

Protoplanets heated, separating heavy and
light minerals

Larger bodies cooled slower, with heavy
materials settling over longer times into
central cores