Transcript Jupiter - Copeland Science Online

Planet Jupiter
• Fifth planet from
Sun.
• Largest planet.
• Twice as massive
of all the other
planets combined.
Earth Comparison
• Orbit:
5.20 AU
• Diameter:
11.2 Earths
• Mass:
318 Earths
History
• Jupiter (Jove) was the King of
the Gods (Zeus).
• Fourth brightest object in the
sky from Earth.
• Known as a “wandering star”
since prehistoric times.
• Galileo (1610) used telescope
to discover four moons.
Moon Preview…
The Moons
o Galilean moons are easily visible with
binoculars; a few bands and the
Great Red Spot can be seen with a
small telescope.
Io
Europa
Ganymede
Callisto
Moon Discoveries
• The Moons were the first discovery of
a center of motion not associated with
Earth.
• Satellite motions and phases of
Venus helped support Copernicus's
heliocentric theory.
o Jupiter has 67 known satellites; the
four large Galilean moons plus many
more small ones, some of which have
not yet been named.
•Isonoe
•Sponde
•Harpalyke
•Arche
•Chaldene
Jupiter’s Moon Names
•Taygete
•Thyone
•Erinome
•Leda
•Eurydome
•Karpo
Named for figures in the life of Zeus,
Whew!
mostly his numerous lovers.
•Io
•Ganymede
•Metia •Carme
•Kale
•Kalyke
•Aoede
•Amalthea
•Pasithee
•Ananke
•Elara
•Euanthe
•Hegemone
•Mneme
•Lysithea
•Callisto
•Himalia
•Megaclite
•Praxidike
•Iocaste
•Autonoe
•Themisto
•Eukelade
•Thebe
•Europa
•Aitne
•Helike
•Sinope
•Kallichore
•Callirrhoe
•Euporie
•Cyllene
•Orthosie
•Adrastea
•Pasipha
•Thelxinoe
•Hermippe
Visiting Spacecraft
Visiting Spacecraft
Pioneer 10 - 1973
Pioneer 11 – 1974
Voyager 1 – 1979 flyby
Voyager 2 - 1980
Ulysses -1992
Galileo
• Galileo launched in 1989 and,
after 2 gravity assists from
Earth…
• reached Jupiter in 1995.
• It dropped a probe into
Jupiter’s atmosphere and…
• continued to orbit Jupiter and
observe its moons until 2003.
• In 2003, it was intentionally
flown down into Jupiter’s
atmosphere to be destroyed.
• On the way, it flew past 2
asteroids including IDA 243
which was discovered to have
its own…
• moon.
• In 2007, the New Horizons
space craft flew by Jupiter on
its way to Pluto.
• It used its instruments to
gather data about Jupiter and
its moons.
• The Juno space craft was
launched in 2011.
• In 2013, it got a gravity assist
during a fly-by of Earth.
• Juno will arrive at Jupiter in
2016.
Planet Structure
• No solid surface, the gaseous materials simply
get denser with depth.
• 90% hydrogen
• 10% helium
• Traces of methane, water, and ammonia.
• Similar to primordial Solar Nebula from which
the solar system formed.
• Saturn has a similar composition.
• Uranus and Neptune have much less hydrogen
and helium.
Interior – “Core”
• Knowledge of Jupiter’s interior is
indirect.
• Galileo’s atmospheric probe only
went to 150 km below the cloud tops.
• Jupiter probably has a core of rocky
material amounting to 10 to 15 Earthmasses.
Interior – “Mantle"
• Liquid metallic hydrogen above the core
makes up most of the planet.
• This exotic form of hydrogen is possible
only at pressures exceeding 4 million
Earth atmospheres.
• Liquid metallic hydrogen consists of
ionized protons and electrons.
• It’s an electrical conductor and the source
of Jupiter's enormous magnetic field.
Outer “Layer”
• The outermost layer is composed primarily
of ordinary hydrogen and helium gas.
• Also includes:
• Water
• Carbon Dioxide
• Methane
• The atmosphere we see is just the very
top of this deep layer.
Clouds
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Three layers of clouds consist of…
ammonia ice,
ammonium hydrosulfide and…
a mixture of ice and water.
Weather
• High velocity winds are confined in wide
bands of latitude.
• Winds blow in opposite directions in
adjacent bands.
• The Galilean probe indicates winds are
more than 400 mph and extend down as
far as the probe was able to observe.
• Winds may extend down thousands of
kilometers into the interior.
Band Characteristics
• Chemical and temperature
differences between bands create
colored effects.
• Light colored bands are called zones;
the dark ones belts.
• Complex vortices at boundary regions
were first seen by the Voyager
missions.
Band Characteristics
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Cloud colors correlate with altitude:
Blue = lowest
Brown = higher
Whites = higher yet
Red = no clouds
Sometimes we see the lower layers
through holes in the upper ones.
The Red Spot
• The Great Red Spot (GRS) has been
seen for more than 300 years.
• Discovered by Cassini or Robert
Hooke.
• The GRS is a 12,000 by 25,000 km
oval, big enough to hold two Earths.
The Red Spot
• Infrared observations and its rotation
direction indicate that the GRS is a highpressure region whose cloud tops are
significantly higher and colder than the
surrounding regions.
• There are other spots such as Red Spot
Junior.
• It is not known how such structures can
persist for so long.
Radiation
• Jupiter radiates more energy into
space than it receives from the Sun.
• The interior is hot: the core is about
20,000 K.
• Slow gravitational compression heats
the planet.
Radiation
• Deep heat convection is responsible for
the complex motions we see in the cloud
tops.
• Jupiter does NOT produce energy by
nuclear fusion as in the Sun; it’s too small
and hence its interior is too cool to ignite
nuclear reactions.
• If Jupiter were 80 times more massive, it
would be a small star.
Magnetic Field
• Jupiter has a huge magnetic field,
much stronger than Earth's.
• Its magnetosphere extends past the
orbit of Saturn!
• Jupiter's moons therefore lie within it.
Magnetic Field
• Designers of the Voyager and Galileo
spacecraft had to take in account the
high levels of energetic particles
trapped by Jupiter's magnetic field.
• It would be immediately fatal to an
unprotected human being.
Rings!
• Jupiter has rings like Saturn's, but much
fainter and smaller.
• Unexpected and were only discovered
when two of the Voyager 1 scientists
insisted that after traveling 1 billion km it
was at least worth a quick look to see if
any rings might be present.
• Unlike Saturn's, Jupiter's rings are dark.
Rings!
• Very small grains of rocky material.
• Particles don't stay there long due to
atmospheric and magnetic drag.
• Galileo spacecraft found evidence
that rings are continuously resupplied
by dust formed by micro-meteorite
impacts on the four inner moons.
Comet Impact!
• In July 1994, Comet Shoemaker-Levy
9 collided with Jupiter with
spectacular results.
• The effects were clearly visible even
with small telescopes.
• The debris from the collision was
visible for nearly a year afterward with
HST.
Galilean Moon Facts
Io
Io
• Radically different from any other body in the solar
system.
• A surprise to Voyager scientists.
• Expected to see impact craters like the Moon.
• Very few, therefore, surface is very young.
• Voyager 1 found hundreds of volcanic calderas; some
active!
• Venting material appears to be sulfur or sulfur dioxide.
• The eruptions change rapidly.
• In the four months between Voyager 1 & 2 some
stopped and others started.
• The deposits surrounding the vents also changed visibly.
Europa
Europa
• Few craters; only three craters larger than 5 km in
diameter have been found.
• Surface strongly resembles images of sea ice on Earth.
• Possible that liquid water is below ice, perhaps as much
as 50 km deep.
• Kept liquid by tidally generated heat.
• Only place in the solar system besides Earth where
liquid water exists in significant quantities.
• Streaks crisscross the entire globe up to 20 km across
are produced by volcanic eruptions or geysers.
• Very small oxygen atmosphere.
• Only five others (Io, Ganymede, Callisto, Titan and
Triton) are known to have atmospheres.
Ganymede
Ganymede
• Surface is an equal mix of two types of
terrain:
• Old, highly cratered dark regions
• Younger lighter regions with grooves and
ridges.
• Grooves are of tectonic nature.
• Has its own magnetosphere field
embedded inside Jupiter's huge one.
• Indicates possible liquid iron core.
Callisto
Callisto
• Covered entirely with craters like the highlands
of the Moon and Mars.
• Most cratered surface of any body observed in
the solar system.
• Largest are surrounded by concentric rings
which look like huge cracks but have been
smoothed out by eons of slow movement of the
ice.
• Some craters have collapsed, lacking high ring
mountains.
• Small atmosphere composed of carbon dioxide.