Transcript File - Mr. Ross Brown`s Science Pages

Unit 7: The Outer Planets
Mr. Ross Brown
Brooklyn School for Law and
Technology
In this unit we will learn about:
• Characteristics of the outer planets, how they
compare to each other & to the inner planets
• The internal sources of heat of these planets
• Jupiter’s Great Red Spot
• Why Uranus and Neptune appear blue
• The moons of the gas giants
• Why some of these moons appear geologically
active
• The rings around the gas giants
Why name it after Jupiter?
• 11 January 2016
• Do now: How do Jupiter’s mass, diameter, and
density compare to the Earth’s?
Why name it after Jupiter?
• Jupiter, king of the gods
• Largest planet in our Solar
System, mass and diameter
• Mass > all other planets
combined
• 10x Earth’s diameter, >300x
mass
Why name it after Jupiter?
• Atmosphere: mostly
Hydrogen, Helium, and
hydrogen-rich Methane
(CH4,) Ammonia (NH3,) and
Water (H2O)
• Clouds of H2O ice and NH3
• Clouds spin over planet
faster than on Earth
• Jupiter rotates once every 10
hours, equator bulges
Jupiter’s Interior
• All based on theory
• Mass calculated by observing gravitational
attraction on moons
• Once we calculate radius we can obtain
volume, and thus density
• Jupiter’s is 1.3 g/cm3) (Water is 1, Earth is 5.5)
• Composed of light elements (H2)
Jupiter’s Interior
• Tremendous gravity holds it all together
• Deep inside compressed to 3x density of iron
Jupiter’s Interior
Jupiter’s atmosphere
• Jupiter’s heat radiates up to space, cools and
drops in convection currents.
• Jupiter’s speedy rotation produces a strong
Coriolis effect
• Strong winds, > 300 kpm (200 mph)
Coriolis Effect
Coriolis Effect on Jupiter
Coriolis Effect on Jupiter
• Conflicting currents create vortices
• Great Red Spot, first identified in 1600s
Jupiter’s Magnetic Field
• Convection of metallic liquid hydrogen core 
magnetic field much stronger than Earth’s
Jupiter’s Magnetic Field
• Aurora
Jupiter’s Rings
• Very thin, hard to see
• Tiny particles of rock dust held by gravity
Jupiter’s Moons
• Galilean moons (Io, Europa, Ganymede,
Callisto) are very large
– All but Europa are larger than our Moon
– Ganymede is largest moon in our Solar System
– Amalthea, 5th largest, is much smaller
Io
• Closest to Jupiter
• Between Jupiter and Europa, tremendous tidal
forces generate heatvolcanoes (sulfurs)
Europa
• Smallest Galilean moon
• Crust of ice, cracked, with frozen mineral-rich
water seeping through cracks
Ganymede and Callisto
• Appear like our Moon but surface is mostly ice
• Callisto may have water like Europa
Galilean Moon Densities are Highest
Jupiter’s Other Moons
• Much smaller, most likely captured asteroids
• Tilted orbits
Homework #12
• 12 January 2016
• If Jupiter were moved closer to the Sun, what
do you think would happen to it?
Why name it after Saturn?
• 19 January 2016
• Do now: How do Saturn’s mass, diameter, and
density compare to Earth’s?
Why name it after Saturn?
How does Saturn differ from Earth?
• 2nd largest in solar system, twice as far from
Sun as Jupiter (10 AU)
• Diameter 9.5x Earth, mass 95x Earth, but
density is only 0.7 g/cm3
• Largely hydrogen & hydrogen-rich compounds
About those rings….
• Very wide, very thin
– From 30,000 km above atmosphere to 136,000 km
– Only a few hundred meters thick
– And very small (centimeters) particles
About those rings….
About those rings….
• Gaps
– Caused by gravity of tiny moons orbiting Saturn
– Shepherding satellites: two moons in a close,
common orbit
Homework #13
• 19 January 2016
• What are the rings of Saturn made of? How do
astronomers know this?
Where do planetary rings come from?
• 20 January 2016
• Do now: Where indeed do planetary rings
come from?
Where do planetary rings come from?
• Not just Saturn
– Easier to see from side of planet away from Sun
• How old are they?
– From planet’s origin or trapped particles?
– Why not clump and form a moon?
Why didn’t Saturn’s rings become a
moon?
• The Roche Limit
– If a moon gets too close to a planet, gravity could
rip it apart
– The point where this occurs is 2.44 planetary radii,
called the Roche Limit
Saturn’s Moons
• One very large and 61 smaller
Saturn’s Moons
Saturn's Moons
• Less dense than Galilean moons
– Ice interior?
• Most are heavily cratered meaning……?
• 21 January 2016
• Do now: What have we learned about the
Outer, or Jovian, or Gas Giant planets?
What’s so special about Uranus?
• 22 January 2016
• Do now: Why does Uranus appear blue?
What’s so special about Uranus?
• Diameter 4x Earth, mass 15x
• 19 AU from Sun
• 1781, first observed by Herschel
– First thought it was a comet
What’s so special about Uranus?
• Of course, rich in hydrogen
– Water, ammonia, methane
– Methane gas absorbs red light, thus Uranus
appears blue
• Density 1.27 g/cm3
– Compare to Jupiter and Saturn
What’s so special about Uranus?
• That tilt, tho!
– Equator almost perpendicular to orbit
Uranus’ Tilt
Uranus’ Moons
• 5 large moons and about 20 smaller
What does our study of the other
planets tell us about Neptune?
• 25 January 2016
• Do now: What are the principal components
of Neptune’s atmosphere? And what can you
predict about its inner structure?
What does our study of the other
planets tell us about Neptune?
• Similar to Uranus in size
– Diameter 3.9x Earth, mass 17x
– Blue
– 30 AU from Sun, so hard to study
• Voyager 2 mission 1989
– Encircled by bands
– Large dark blue spot
• Perhaps no longer there today
What does our study of the other
planets tell us about Neptune?
What does our study of the other
planets tell us about Neptune?
• Discovered from predictions
– Separately by English & French astronomers 1840s
– Saw that Uranus didn’t follow a predicted orbit, so
they knew something was there
What does our study of the other
planets tell us about Neptune?
• Structure similar to Uranus
– Planet is a hot mixture of ammonia, water, &
methane
– Atmosphere is hydrogen/ hydrogen compounds
– Density 1.67
– Light atoms but as core of silicon and iron
What does our study of the other
planets tell us about Neptune?
• Atmosphere
– Blue, so methane atmosphere
– Cloud bands
• Coriolis effect, rotates every 16 hours
– Winds over 2200 km/ hour at equator
• Radiates energy, perhaps from its creation, creating
convection
Neptune’s Moons
• 6 small moons in close, circular orbit, and 7
much further away
• Triton, as big as Jupiter’s Europa, orbits
backwards (clockwise)
– From Kuiper Belt?
• So massive it has its own atmosphere!
Triton
Streaks from geysers
Comparison of Solar System Objects