Transcript The Outer Planets

The Outer Planets
Chap 16, Sec 4
Chap 16 Sec 4 Essential
Questions
1. What characteristics do the
gas giants have in common?
2. What characteristics
distinguish each of the outer
planets?
The Gas Giants
The Gas Giants
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The four outer planets
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Jupiter
Saturn
Uranus
Neptune
Much larger & more massive than Earth
Do not have solid surfaces
All are composed mainly of hydrogen & helium
Their gravitational force is much greater than Earth’s because of
their massive size
They have thick atmospheres
A lot of the hydrogen & helium inside the planets is liquid because of
enormous pressure
Outer layers of the planets are cold because of their distance from
the sun, but temperatures increase inside the planets
All have many moons
All have rings
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A ring is a thin disk of small particles of ice and rock
Jupiter
Jupiter
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The largest & most massive planet
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Its mass is about 2 ½ times all other planets
combined
Atmosphere:
Thick atmosphere of mainly hydrogen &
helium
 The Great Red Spot – a giant storm larger
than Earth. Swirling winds blow hundreds of
miles an hour, similar to a hurricane, but it has
lasted for 350 years and doesn’t appear to be
weakening
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Jupiter
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Structure:
A dense core of rock and iron at the center
 The core is surrounded by a thick mantle of
liquid hydrogen & helium
 Pressure at Jupiter’s core may be 30 million
times greater than the pressure at Earth’s
surface
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 Extreme
pressure is caused by its thick
atmosphere
Jupiter’s Moons
Remember Galileo discovered the largest
four
 Many more have been discovered as
technology improved – latest count is
more than 63
 The four largest are all very different from
each other and are all larger than our
Moon
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Jupiter’s Largest Moons
Io – its surface is covered with large,
active volcanoes. Sulfur gives it an
unusual color.
 Europa – it has an icy crust and scientists
suspect it has an ocean of liquid water
underneath the ice
 Ganymede – the largest moon in the solar
system is larger than Mercury or Pluto
 Callisto – has an icy, cratered surface
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Io
Ganymede
Europa
Callisto
Saturn
Saturn
The second-largest planet
 Has a thick atmosphere of hydrogen &
helium
 Atmosphere has thick clouds and storms –
though not as spectacular as those on
Jupiter
 The least dense planet (less dense than
water)
 The Voyager probes provided lots of
information about Saturn
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Saturn’s Rings
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Saturn has the most spectacular rings of
any planet
The rings are broad and thin – like a CD
 The rings are made of chunks of ice and rock,
each traveling in its own orbit around Saturn
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Saturn’s Moons
Saturn is currently known to have more
than 60 moons
 The largest is Titan
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It has a very thick atmosphere (so thick that
light can hardly pass through)
There are four other moons that are larger
than 1,000 kilometers in diameter
Two views of Titan
From Far Away
Very Close Up with
special Lens
Uranus
Uranus
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It is about four times the diameter of Earth,
but much smaller than Jupiter and Saturn
It is twice as far from the sun as Saturn, so it
is much colder
Has a unique blue-green color because of
methane gas in its atmosphere
Its rings are thin, flat, and much darker than
Saturn’s
It was the first planet discovered since
ancient times
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Discovered in 1781 by Willam Herschel in
England
Unique Features of Uranus
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In the 1980s (200 years after being
discovered) Voyager 2 arrived at Uranus and
sent back close-up pictures
It has few clouds, but astronomers calculated
it rotated in about 17 hours
Uranus is tilted on its side
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It rotated top to bottom instead of side to side like
other planets (and its rings and moons rotate
around its tilted axis)
Scientists think it was hit by an object billions of
years ago that knocked it on its side
Uranus’s Moons
Uranus has at least 27 moons
 Voyager 2 discovered the five largest
moons have icy, cratered surfaces and
lava flows
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Neptune
Neptune
Neptune is similar in size and color to
Uranus
 It is a blue color because of methane in its
atmosphere
 Because it is so far from the sun, it is very
cold
 It has clouds and storms in its atmosphere
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Scientists think the clouds and storms are
happening because the planet is slowly
shrinking and causing the interior to heat up
Discovering Neptune
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Neptune was discovered by mathematics
– astronomers noticed Uranus’s orbit
wasn’t the exact path it should be and
predicted an unseen planet was disturbing
Uranus’s orbit
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By 1846 scientists had calculated the orbit of
the unseen planet – soon after, Neptune was
identified
Flying by Neptune
In 1989 Voyager 2 flew by Neptune and
photographed the Great Dark Spot (a
storm about the size of Earth)
 Storms come and go on Neptune which
tells us it has an active atmosphere
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Neptune’s Moons
Neptune has at least 13 moons
 The largest is Triton
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It has a thin atmosphere
 Its south pole is covered in nitrogen ice
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Pluto
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Pluto is not a gas giant
It is much smaller and denser than the outer
planets and has a solid surface
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Pluto is so far from the sun that it takes 240
Earth years to revolve around the sun once
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Pluto is smaller than our Moon
Its orbit is very elliptical and it crosses inside
Neptune’s orbit for part of its revolution
Moons
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Pluto has at least three. The largest is Charon
and is more than half as big as Pluto
Dwarf Planets
Dwarf planets are round and orbits the
sun, like a planet, but it has not cleared
out the neighborhood around its orbit
 Dwarf planet classification was created in
2006 when an object larger than Pluto and
farther from the sun was discovered
 At that time Pluto was reclassified as a
dwarf planet and there are two others
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Video
Essential Questions - Answered
1.
What characteristics do the gas giants
have in common?
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No solid surface
Thick atmosphere made mostly of hydrogen
& helium
A set of rings
Very Large & massive
Rotates quickly, revolves slowly
2. What characteristics distinguish each of
the outer planets?
Jupiter – largest & most massive planet, Great
Red Spot, most moons (63+)
Saturn – second largest planets, best rings,
least dense planet
Uranus – blue-green color, rotates on its side
Neptune – blue color, lots of storms
Pluto – solid, rocky surface; no longer a planet