Transcript Chapter 3 The Solar System How was it formed  The Nebular Theory  Started as nebula about 5 billion years ago – Composed of.

Chapter 3
The Solar System
How was it formed
 The
Nebular Theory
 Started as nebula about 5 billion years ago
– Composed of hydrogen and helium
 Nearby supernova sent shock waves
through galaxy
– caused gases to be pulled inward
– supplied new elements
 Shrank to a spinning disk –10 billion
kilometers across
 Gravity heated center to protostar - the sun
How was it formed
 Other
matter spun around the new sun
 gathered into clumps- protoplanets
 Near the sun the light weight gases
boiled away
– Mercury, Venus, Earth, Mars
 In those far away the gases did not boil
away
– Jupiter, Saturn, Uranus, Neptune
– the gas giants
How was it formed
 Around
the protoplanets smaller clumps
formed moons or satellites.
 Pluto is thought to be a moon of Neptune
that broke away.
 Asteroid belt- clumps of rocks between
Mars and Jupiter
 Jupiter’s gravity stopped a planet from
forming
 Oort Cloud- Near the edge clumps of
matter- home of comets.
History
 People
have used the stars for ages.
 Used constellations to set planting times
 Used constellations to guide travels
 Some lights in the sky wandered through
the constellations
 Called them “planets” which is Greek for
wanderers
Ptolemy
 Greek
scientist
 Placed earth at center of universe
 Other objects moved in orbits around the
earth
 Because circle was considered a perfect
shape, thought they moved in circular
paths
Copernicus
 Polish
astronomer
 Found Earth and planets revolved around
sun
 In the same direction
 At different speeds
 Thought the orbits were circular
Kepler
 German
mathematician and astronomer
 Used others observations (Tycho Brahe)
 Calculated the orbits of planets were
ovals or ellipses
 Closer to the sun - shortest time of orbit
 Farther from the sun - greater time
Planets
 Move
in an elliptical orbit
Planets
 Period
of revolution
 the time it takes to go once around the
sun
 one year
 Mercury 88 days, Pluto 248 years
What keeps them there?
of inertia - objects motion won’t
change unless acted upon by an outside
force.
 Won’t change speed or direction
 Why do they curve?
 Gravity pulls them toward the sun
 Law
What keeps them there?
Rotation
 Planets
spin on their axes
 One rotation is a day
 Mercury 58 days, Jupiter 10 hours
Special Features of the
 Mercury
Planets
 Many
Craters
– no atmosphere
– no erosion
 Slow rotation
makes it hot and
cold
 Thick
Venus
atmosphere of
carbon dioxide
 Sulfuric acid clouds
 Greenhouse effect
– carbon dioxide traps
heat.
– Makes Venus hotter
than Mercury
 Retrograde rotation rotates backward
Mars
 Red
planet- covered by
iron oxide (rust)
 Mons Olympus  Largest volcano in the
solar system
 Two ice caps
– north - water -never melts
– south -carbon dioxide
melts in summer
Two moons of Mars
Phobos
Deimos
Jupiter
Jupiter
 Largest
of the gas giants
 Huge storms - red spot
 Small solid core
 Liquid metal layer makes a huge
magnetic field
 Magnetosphere
 Gives off more heat than it receives from
the sun
 Thin ring
Jupiter
 Gives
off more heat than it receives from
the sun.
 By far the largest planet.
16 moons
4
seen by
Galileo helped
change science
Saturn
 Similar
to Jupiter
 Clouds, magnetosphere, gives off heat
 Rotates in 10 hours - makes it bulge in
the middle and flat at the poles
 Low density- would float in water
Saturn
 Many
rings
– complex system
– made of water
– weave in and
out
Saturn
 Many
moons  Titan- the largest is
like the early Earth.
Uranus
 Twice
as far from the
sun as Saturn.
 Covered with ocean
of superheated
water
 Tilted on axis
 Rings of methane
ice
 Many moons
Neptune
 Like
Uranus
 Hydrogen and
helium
atmosphere
 Surface of water
and methane
 Rings made of
dust
 Eight moons
Triton
 Large
moon
 Thought to be
captured
 Retrograde
revolution
 out of plane of
Neptune’s rotation
Pluto
 Moon
sized
 Made of methane
 Pink atmosphere on the sunny side
 Moon Charon 1/2 the size of Pluto
 Scientists think it is a moon broken away
from Neptune
– Orbit crosses Neptune
– Orbit not in plane with other planets
Other Stuff
 Meteor-
the shooting star -the light you
see the sky
 Meteoroid- solid rocky objects circling the
sun
 Meteorite- When a meteor hits the ground
 Most don’t because they burn up in the
atmosphere
 Some meteoroids are iron and nickel
 Some are stony
 Others are combinations
Meteorites
 Leave
a crater where they hit the ground
 Meteorite Crater in Arizona
 Evidence of meteorites from the moon
and from Mars
Comets
 Chunks
of dust and gas from the Oort
Cloud that orbit the sun
 When it gets close to the sun it gets
hotter
 Some of the gas and dust form a cloud
around the head called the coma
 Solar wind pushes the gases away from
the sun and make the tail
 Tail is pushed by the solar wind
 Tail always points way from the sun
Coma
Tail
Nucleus
Solar wind
Comets
 Comets
orbit the sun
 Long period comets take a long time to
go around
– Thousands of years
 Short period comets return every few
years
– Halley’s every 75 to 79 years
– Last time in 1986
 Suspect a nearby star disrupts the Oort
cloud to send more comets toward sun.
Asteroids
 Chunks
of planetlike material floating in
space
 Most between Mars and Jupiter
 Most 1km in diameter
 Ceres- 1000km in diameter
 Some pass near Earth
 Caused craters on moon, and inner
planets
Looking for life
 On
other planets
 Need liquid water and moderate
temperatures.
 Earth is just the right distance to have the
right temperatures
 Looking for evidence of former life on
Mars- used to have water.
 On Titan atmosphere like early earth.
Rockets
 Rely
on Netwon’s Third law of Motion
– For every action there is an equal and
opposite reaction.
 Reward blast of hot gases causes rocket
to shoot forward.
 First developed by Chinese in 1000
– Tube full of gunpowder with cap on one
end.
Escape Velocity
 The
minimum speed needed to leave the
gravitational pull.
 Depends on mass of planet and distance
from the center of planet.
– Earth 11.2 km/sec
– Moon 2.3 km/sec
– Jupiter 63.4 km/sec
– Pluto 0.3 km/sec
– Sun 616 km/sec
Rockets and Escape
Velocity
 Solid
rockets burn up fuel quickly
– Large thrust early
– Gravity eventually slows them down.
 Liquid fuels provide continuous thrust.
– Goddard- gasoline and liquid oxygen
– Space shuttle liquid hydrogen and
liquid oxygen
 Multiple stages to reduce weight.
Spacecraft
 Probes
have gone past all the planets
except Pluto
 Have sampled comets tails
 Have taken pictures of planets and
moons.