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What are planets?
Planet- a Greek word for wanderer
Planets
• Dark bodies that
revolve around
stars—(sun)
• Do not produce
light
• Made of rock,
metal and gas
• Rounded shape
• Dominate their own
“neighborhood”—
clear of other
celestial bodies!
Planets vs Stars
Planets
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Reflect light
Orbit stars
Can be solid, liquid, gas
Round shape
Don’t twinkle
Stars
• Nuclear reactions which
produce heat and light
• Twinkle
• Made mostly of
hydrogen and helium
• Some are small, but
others can be millions of
times bigger than our
Sun!
Planets
• Reflect sun
light
• Move in 2
ways: revolve
around the sun;
and rotate
How Did It All Begin?
• One theory is the Solar system began
billions of years ago, when gases and dust
began to come together to form the Sun,
planets, and other bodies of the solar
system.
• 99.8% of matter in our solar system is in the
sun! The rest makes up the planets, moons
and all the other gases, rocks, and dust!
NEBULA
PROTOSTAR
STAR
SUN, PLANETS, MOONS,
COMETS, ASTEROIDS….
Ya Gotta Have Sol!
SUN VIDEO
OUR SUN “SOL”
• Largest object in solar system (makes up 99.8% of
mass of solar system!)
• About 5 billion years old (half way there!)
• Average surface temperature of 6,000°C
• “Only” 93 million miles away! “Goldilocks Zone”
• Can hold about a million Earth’s inside!
• More than 400 Earth’s could fit across the
diameter
• It’s the source of all life on Earth
• One day will exhaust its fuel and collapse into a
white dwarf (after it expands and takes out the
inner planets! Don’t worry—it’s a long way off!)
Terrestrial Planets
• Mercury
• Venus
• Earth
• Mars
Mercury
Mercury
MERCURY
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Roman messenger of gods
88 days to orbit the sun
59 days to rotate
Rotates very slowly
Has many craters
Very thin atmosphere
Can be as hot as 800° F and as cold as
-300°F
Caloris Basin
Venus
Venus
VENUS
• Roman goddess of love and beauty
(Aphrodite Greek)
• Lifeless and dry
• Atmosphere is mostly thick clouds of
carbon dioxide
• “Morning or evening” star
• A year is only 225 days, but a day is
243 earth days!
• Rotates east to west
• Hottest planet
• Massive volcanoes and lava flows
Venusian Volcano
Venus Magellan
Mapped 99% of Venus’ surface
The “morning star”…
Earth
EARTH
• The “Goldilocks” planet- JUST
RIGHT!
• Atmosphere mostly nitrogen (about
78%) and 21 % oxygen.
• Water planet
• Solid and liquid core
• Earth’s tilt gives us seasons
• Suitable temperatures for life
• Only planet not named after myth
Mars
Mars
MARS
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Roman god of “War” (Ares- Greek)
Nicknamed the “Red Planet”
Has seasons—primarily summer and winter.
Moons named Phobos and Deimos
Has north and south pole
Summers can warm to 80°F but can get as
cold as -280°F
• Home to Olympus Mons, largest volcano in
solar system
• Global Surveyor found signs of water!
SPIRIT AND OPPORTUNITY
MarsChallenges-EDL
http://www.youtube.com/watch?v=8u6gNH6xIfc
http://marsrovers.jpl.nasa.gov/gallery/video/animation.html
MarsRover
Opportunity watches the sunset---November
2010
Moons of Mars
photographed by Spirit
• Asteroids are objects left over rocky
objects from the formation of the Solar
System, that never fully developed into
planets.
The Galileo spacecraft photographed Ida and
Gaspra on its way to Jupiter. They are the
only asteroids which have been studied
closely.
Outer Planets
(Gas Giants)
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Jupiter
Saturn
Uranus
Neptune
Jupiter
JUPITER
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King of the Roman Gods (Zeus- Greek)
Gas giant
Largest planet
Complex weather systems
Giant red spot is swirling mass of gas- 3x
size of earth- huge storm has raged there for
centuries!
• 64 moons! (as of 2007)
• Radiates more energy than it gets from the
sun
• Very strong gravitational pull
http://science.discovery.com/videos/space-school-jupiter.html
GALILEO
Saturn
Saturn
SATURN
• Roman god of agriculture (Ceres Greek)
• Famous for its rocky, icy rings- up to 180,000
miles across
• Very light- could float in water
• 62 moons (and growing!)
• Cassini spacecraft recently explored the rings
• Evidence of lakes of water and ammonia on Titanlargest moon
• Titan has an atmosphere of nitrogen, 10x more
than earth! Also possible underground oceans!
Saturn's Flashdance of Lightning
Saturn’s Rings
• http://science.discovery.com/videos/saturn/
CRANK UP THE HEAT!
Saturn's moon Enceladus
is pumping out 2.6 times
as much heat as all the
hot springs in the
Yellowstone region. The
outpouring of energy
significantly boosts the
likelihood that an ocean
of liquid is sealed beneath
the moon's icy surface.
Water, in turn, is
considered a key
ingredient for life
Uranus
URANUS
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Giant ball of gas and liquid
Spins sideways on its axis
First sky god, father of Saturn
29 moons
Very cold temperatures and methane
gas give it the blue-green color
• Very gusty winds (600 mph)
Neptune
NEPTUNE
• Roman god of the sea (Poseidon Greek)
• Atmosphere with very violent wind storms1500mph!
• Sometimes is further than Pluto- orbits
cross in ellipse
• 13 known moons
• Last of the main stream planets!
• Voyager discovered rings around in 1989
Neptune
Pluto
PLUTO
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Now a “Dwarf” or “Planetoid”
God of the Underworld (Greek- Hades)
Very small, icey object
Possibly a remain of a Kuiper Belt object
Hubble Telescope saw ice caps (not likely
in form of water)
• Its moon Charon is similar to it- sometimes
called its Twin
• 248 years to go around sun!
Kuiper Belt
• The outer edge of our
solar system is not empty.
There are many, many
huge spheres of ice and
rock out near Pluto’s orbit.
Astronomers call this huge
group of planetoids
"Kuiper Belt Objects", or
"KBOs" for short. The
Kuiper Belt a bit like the
asteroid belt, but much
farther from the Sun.
Pluto is part of the Kuiper
Belt.
Eris
ERIS
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Formerly UB-313 or Xena
Also a “Dwarf”
Goddess of Warfare and Strife
1 moon- Dysnomia
Larger than Pluto
Kuiper Belt object
Almost 10 billion miles to sun!
Most distant object ever seen to orbit sun!
Estimated time around sun is anywhere from 550700 years!