Transcript Ch. 17: The Solar System

17-1: What is the Solar System
The
Sun contains 99.85% of
all the matter in the Solar
System.
The planets revolve around
the Sun in orbits
Most planets orbit the sun in a
counter-clockwise fashion
 Nebula
spinning cloud of
gas and dust in space
 One theory to explain how the
solar system formed is a nebula
 http://www.picturethecosmos.co
m/
Inner Planets: Small Rocky Worlds
Planets – are small,
dense, rocky worlds with less
atmosphere than the other type of
planet.
 Terrestrial
 They have craters, no rings, very few
moons, very small.
○
Mercury
○
Venus
○
Earth
○
Mars
Outer Planets: Gas Giants
Planets – are large, gaseous,
low density worlds. Thick gaseous
mostly hydrogen atmospheres, rings,
lots of moons, and very large in
comparison to terrestrial planets.
 Jovian
 Jupiter
 Saturn
 Neptune
 Uranus
Pluto
– doesn’t fit either
category. Pluto is a small icy
world clearly different from
either the Jovian and Terrestrial
worlds.
Pluto
Sun’s Family
 Sun’s
family consists of 8
planets, > 162 moons, & at
least 3 dwarf planets
17-2 Orbits
 Gravity
force of attraction btw 2
objects with mass
 Gravity keeps the planets in orbits
flying around the Sun
 All planets travel in elliptical orbits
 Planets travel fastest at perihelion
(closest to Sun) & slower at
aphelion (farthest from Sun
17-3 Our Moon
 American
landed on the Moon
on July 20,1969
 The Moon’s gravity is 1/6 that of
Earth
 The Moon has no liquid water
 Temp. ranges from 100°C to
below -200°C (100°C is boiling)
17-3 Features of Our Moon
 Maria
smooth, dark areas on
the Moon that are broad, flat
plains; maria means “seas”
 Light areas that are mountains
or highlands; some are higher
than on Earth
 Craters caused by large objects
striking the surface or erupting
volcanoes
17-4 Other Moons
 Satellite
an object that
orbits another body in space
 Moons are natural satellites
 All planets except Mercury &
Venus have 1 or more moons
Moons of the Inner Planets
 Mercury
has 0 moons
 Venus has 0 moons
 Earth has 1 moon
 Mars has 2 moons; Deimos &
Phobos
Moons of the Outer Planets
 Jupiter
has at least 63 moons;
Ganymede,Callisto, Io, & Europa
are the 4 largest
 Saturn has 59 moons; Titan is the
largest
 Uranus has 27 moons; Titania &
Oberon are the largest
 Neptune has 13 moons; Triton &
Nereid are visible
17-5 Mercury
 Mercury
closest planet to the
Sun
○Dry
○Rocky
○No atmosphere
○Temp. ranges from 430°C to 170°C
○Covered with craters
17-5 Venus
 Venus
similar to Earth in size,
mass, & density
Very hostile environment
Highest temp. of all planets
90 times more air pressure than Earth
Carbon dioxide atmosphere & clouds of
sulfuric acid cause a runaway
Greenhouse Effect
Retrograde rotation (east to west)
Has smooth plains, mountains, valleys
17-5 Earth
 Third
planet from Sun
 Only planet with oceans of liquid
water
 Only planet with life because it
has moderate temp., liquid water,
& atmosphere w/ O2
17-6 Mars
 Fourth
planet from Sun
 Orbit period687 days;
rotation24 hr. 37 min.
 ½ diameter of Earth
 Has volcanoes, polar icecaps,
craters, river channels
 Thin CO2 atmosphere
 No visible water
17-6 Mars cont.
 Cold,
dry world; colder than
Antarctica in winter, as warm
as the Midwest in spring
 Winds up to 100 km/h cause
dust storms
 Volcanoes bigger than Earth
Mars has less gravity
 Canyon bigger than U.S.
17-7 Asteroids & Meteoroids
 Asteroid
belt btw. Mars &
Jupiter
 Asteroids leftover debris
from the formation of solar
system that orbit the Sun
 Pieces of rock and metal
17-7 cont.
 Meteoroids
small chunks of
asteroids that travel in space
 Meteor rock or metal that
enters a planet’s atmosphere
 Meteorite rock that hits a
planet’s surface
17-8 Jupiter
 Largest
planet
 5th planet from Sun and 1st
gas giant
 Made up mostly of Hydrogen
and Helium
 Has faint rings of ice and dust
 Best known feature is Great
Red Spot raging hurricane
17-8 Saturn
 2nd
largest planet
 6th planet from Sun & 2nd gas giant
 Made mostly of Hydrogen &
Helium
 Least dense of all planets; would
float in water
 Best known for its rings
17-9 Uranus
 3rd
largest planet
 7th planet from Sun & 3rd gas giant
 Made mostly of Hydrogen and
Helium
 Atmosphere contains methane
 Appears to lie on its side
 Has faint rings
17-9 Neptune
 4th
largest planet
 8th from Sun & last gas giant
 Made mostly of Hydrogen & Helium
 Upper atmosphere is methane
 Has Great Dark Spot similar to
Jupiter’s Great Red Spot
 Winds blow east to west @1500
km/h
17-9 Dwarf Planets
 In
2006 Pluto was reclassified
as a dwarf planet
 Dwarf planet small,
planetlike object that orbit the
Sun, but share their orbits with
other objects
 Pluto, Ceres, Eris
17-9 Kuiper Belt
 Kuiper
belt is btw Neptune &
outer regions of solar system
 100 million fragments of ice &
rock
 Includes dwarf planets & their
moons
17-10 Comets
 Comet
lump of ice, frozen gas,
& dust
 Orbit the Sun in long, ellipses that
go beyond Pluto
 Has 3 parts:
 Nucleus dirty ice ball
 Coma cloud of gas surrounds
 Tail(s) melting particles that point
away from the Sun
17-10 Comets cont.
 Comets
come from the Oort
Cloud
 Far beyond Neptune’s orbit
 May contain trillions of
inactive comets