Download Last Class Today`s Class Jupiter

4/12/2015
Today’s Class: The Giant Planets – Jupiter & Its moons
April 13, 2015
Homework:
1. Reading: Saturn at
http://en.wikipedia.org/wiki/Saturn
2. Mankind Beyond Earth, p. 225-231.
Last Class
• The atmosphere of Venus.
• Greenhouse Effect on Venus & Earth.
• How did Earth’s atmosphere end up so
different from Venus?
– Effects of water and carbon
– Dangers of human activity
Astronomy 2020 – Space Astronomy & Exploration
Clicker Question: What is the leading
hypothesis for Venus’ lack of water?
Clicker Question: What is the leading
hypothesis for Venus’ lack of water?
a) It’s water molecules were broken apart, and
hydrogen was lost to space.
b) Venus formed closer to the Sun and accreted
very little water.
c) Its water is locked away in the crust along
with carbon.
d) Active volcanoes absorbed all the water early
in the evolution of Venus.
a) It’s water molecules were broken apart, and
hydrogen was lost to space.
b) Venus formed closer to the Sun and accreted
very little water.
c) Its water is locked away in the crust along
with carbon.
d) Active volcanoes absorbed all the water early
in the evolution of Venus.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Today’s Class
Jupiter
• Inside Jupiter
– Source of heat
– Magnetosphere
• Atmosphere of Jupiter
• The moons of Jupiter
– Io: Active volcanoes
– Europa: Possible ocean & life?
Astronomy 2020 – Space Astronomy & Exploration
• Much farther from
Sun than inner
planets
• Mostly H/He; no
solid surface
• 300 times more
massive than Earth
• Many moons, rings
Astronomy 2020 – Space Astronomy & Exploration
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4/12/2015
Jupiter’s moons
Inside Jupiter
Jupiter's
moons can be
as interesting
as planets
themselves,
especially
Jupiter's four
Galilean
moons.
•
•
•
•
Io (shown here): active volcanoes all over
Europa: possible subsurface ocean
Ganymede: largest moon in solar system
Callisto: a large, cratered "ice ball"
• High pressures
inside Jupiter cause
phase of hydrogen
to change with
depth.
• Hydrogen acts like a
metal at great
depths because its
electrons move
freely.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Jupiter's Internal Heat
Jupiter's Magnetosphere
• Jupiter radiates
twice as much
energy as it receives
from the Sun.
• Energy probably
comes from slow
contraction of
interior (releasing
potential energy).
• Jupiter's strong magnetic field gives it an enormous
magnetosphere.
• Gases escaping Io feed the donut-shaped Io torus.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Clicker Question: Jupiter does not have a large metal
core like the Earth. How can it have a magnetic field?
Clicker Question: Jupiter does not have a large metal
core like the Earth. How can it have a magnetic field?
a) The magnetic field is left over from when
Jupiter accreted.
b) Its magnetic field comes from the Sun.
c) It has metallic hydrogen inside, which
circulates and makes a magnetic field.
d) Its core creates a magnetic field, but it is very
weak.
a) The magnetic field is left over from when
Jupiter accreted.
b) Its magnetic field comes from the Sun.
c) It has metallic hydrogen inside, which
circulates and makes a magnetic field.
d) Its core creates a magnetic field, but it is very
weak.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
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4/12/2015
Jupiter's Atmosphere
Jupiter's Colors
• Hydrogen compounds
in Jupiter form clouds.
• Different cloud layers
correspond to freezing
points of different
hydrogen compounds.
• Ammonium sulfide clouds (NH4SH) reflect red/brown.
• Ammonia, the highest, coldest layer, reflects white.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Why are Jupiter's Galilean moons so
geologically active?
Io's Volcanic Activity
• Io is the most volcanically active body in the
solar system, but why?
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Io's Volcanoes
Tidal Heating
• Volcanic eruptions continue to change Io's
surface.
Astronomy 2020 – Space Astronomy & Exploration
Io is squished and stretched as it orbits Jupiter.
Astronomy 2020 – Space Astronomy & Exploration
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4/12/2015
Europa's Ocean: Waterworld?
Tidal stresses crack Europa's surface ice
NASA/JPL/DLR
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
Europa's interior also warmed by tidal
heating
Possible Robotic Mission to Europa
Goal: JPL’s Europa Clipper is a
concept that would conduct detailed
reconnaissance of Jupiter's moon
Europa and would investigate
whether the icy moon could harbor
conditions suitable for life. Mission
would perform detailed investigation
of Europa using a radiation-tolerant
spacecraft that would perform
repeated close flybys of the icy
moon from a long, looping orbit
around Jupiter.
Astronomy 2020 – Space Astronomy & Exploration
Astronomy 2020 – Space Astronomy & Exploration
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