Download Chapter 27 – The Planets and the Solar System

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