Transcript Chapter 27 – The Planets and the Solar System

Chapter 27 – The Planets
and the Solar System
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Page 586
Do you think it is possible to count the
rings of Saturn?
The rings look solid in the image, do
you think they are?
What do you think they are made of?
What do we know about the planets?
Chapter 27.1
The Inner Planets
Two Planetary
Neighborhoods
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Inner Planets – Mercury, Venus, Earth,
Mars
All have rocky crust
Dense mantle layers and cores
Because of their Earth like appearance
they are also known as terrestrial
planets
Distance Between Planets
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Outer Planets – Jupiter, Saturn, Uranus,
Neptune and Pluto
1st four are called Jovian – or Jupiter like
Very large gaseous planets with no rocky
crust
Low density due to size
Have ring systems
Pluto is an oddball – not dense enough to
be terrestrial; too small to be Jovian
Mercury
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Nearest to the Sun
Orbits the sun in 88 days
Smallest of terrestrials
Mercury surface resembles the
moon’s
Rotates every 59 days
Temperature – day 400°C; night –
200°C
Chapter 27.2
Venus – Earth’s Sister
Planet – 2nd planet from
the Sun
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Near each other similar in
diameter, mass and gravity
Venus is the only planet to rotate
from east to west
Rotates every 243 days
Orbits every 225 days
Thick yellow clouds make surface
impossible to see
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Magellan radar mapped it
Fault system
Yellow clouds made of sulfuric acid
Surface is hot due to greenhouse
effect (CO2) causing surface to be
475°C
Visible from Earth in the morning
or early evening – “evening star”
Mars – 4th planet from the
Sun
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687 day orbit
Axis tilted about the same as
earth’s giving it seasons. However
they are 2 times as long
Very thin atmosphere (1% of
Earth’s) mostly CO2
Has ice caps – thought to be water
covered by frozen CO2
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Spacecraft have photographed and
landed on Mars surface
Largest known volcano in the solar
system “Olympus Mons”
Has a valley system suggesting
water once ran on its surface
Page 543, 5 Martian landings
Outer Planets
Jovian Planets – Jupiter,
Saturn, Uranus and Neptune
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Much larger than terrestrials –
smallest, Uranus, is 15 times more
massive than earth
No solid surfaces – their “surface”
is an uppermost gas layer
Composed mainly of light elements
H and He
All Jovian planets have ring
systems
Jupiter – 5th Planet from
the Sun
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11.9 year orbit
10 hour rotation
Has 2 times more mass than all the other
planets combined
Radiates 2 times as much energy back into
space as it receives from the sun
Galileo probe entered Jupiter’s atmosphere in
1995 – found no thick clouds and higher than
expected temperatures
Saturn – 6th planet from
the Sun
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30 year orbit
10 hour rotation
Lowest density of all planets, less
than 1
Saturn also radiates more energy
than it receives from the sun, like
Jupiter it has internal heat sources
Uranus – 7th planet from
the sun
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84 year orbit
17.2 hour rotation
It’s rotational axis is tipped almost
completely over
It’s magnetic field is not tipped
Chapter 27.3
Neptune – 8th planet (most
of the time)
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165 year orbit
Rotation 16.1 hours
Neptune was found after
astronomers predicted its location
mathematically in 1846
Winds over 2000 km/hr
Becomes the 9th planet when Pluto
is taken close to the Sun due to
Pluto’s highly elliptical orbit
Pluto
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248 year orbit
Smallest planet in the Solar System
Its moon, Charon, is ½ its size
Most of its atmosphere is frozen.
However, it thaws slightly when it
nears the sun
Planetary Satellites
(moons)
Satellites of Earth and
Mars
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Earth has one moon
Mars has 2 tiny moons, Deimos and
Phobos
Phobos circles mars 3 times a day
Mercury and Venus have no
satellites
Jupiter’s Moons
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At least 63
Galilean moons – Io, Europa,
Ganymede and Callisto are the 4
largest discovered by Galileo
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Io is geologically active
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Nine active volcanoes
No signs of crater impacts
Galileo spacecraft found it has an iron
core surrounded by a molten silicate
rock
Heat on Io is caused by tidal forces
from Jupiter
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Europa
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Surface is thought to be frozen water
It is thought liquid water may exist
under the ice
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Ganymede – the largest
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Larger than Pluto and Mercury
Surface of ice
Callisto – most heavily cratered
object in the solar system
Saturn’s Moons
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At least 31 moons
Largest is Titan
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Only moon in solar system to have a
substantial atmosphere
Uranus’s Moons
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At least 27
5 major moons are Titania, Oberon,
Umbriel, Ariel, and Miranda
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All lack atmosphere and are heavily
cratered
Neptune’s Moons
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At least 13 moons – Triton is the
largest
Solar System Debris
Comets and TNOs (Trans
Neptune Objects)
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Comets described as dirty
snowballs
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Spend most of their time beyond the
orbit of Neptune
Do not become visible until they
travel inside Jupiter’s orbit
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Has 2 parts, nucleus and tail
Tail always points away from the sun
due to solar winds
Most famous comet is Halley’s, it
appears once every 76 years – last
visit 1986
Asteroids – solid rocklike
masses
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Uneven surface causes their
brightness to change
Revolve same direction as planets
Most in asteroid belt between Mars
and Jupiter
Meteors and Meteoroids
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Meteoroid – rock or ice fragment
traveling in space, they differ from
asteroids in that they are smaller
in size
Meteor – when a meteoroid enters
earth’s atmosphere and burns up
“shooting star”
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Meteor shower – occurs when
earth passes into debris left by a
comet that crossed earth’s path –
very predictable, named after the
constellation in the background.
Chapter 27.4
Meteorite
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A large meteoroid that survives earth’s
atmosphere and strikes its surface
3 types
 Stony – resemble earth’s rocks, mostly made of
silicates
 95%
 Irons – mostly iron
 5%
 Stony irons
 <1%
 Most found in the ice of Antarctica
Impact Craters – bowl shaped
depressions that remain after a meteor
or other object strikes earth
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Rare on earth because
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The atmosphere burns up most
meteoroids
Earth is geologically active
Best known is Barringer Meteor
Crater in AZ