ASTR 151 Test #3
Jovian planets share all of the following traits EXCEPT
**low density gaseous core** - strong magnetic fields - lots of hydrogen and helium gas - many moons
Characteristics/effects of Jupiter
- It has benefited life on Earth by sweeping up Solar System debris. - It has a ring system. - It has a strong tidal influence on its moons - It has distinct cloud layers varying in color.
Uranus & Neptune atmosphere
- Uranus and Neptune have atmospheres made of roughly 80% hydrogen, 18% helium, and a small amount of methane - Unlike gas giants, ice giants don't have much ammonia in their atmospheres - Color difference between two planets due to amount of methane present (absorbs red light, too) - Banded structure & storms observed (IR)
Saturn's rings
- extend 7,000 to 80,000 km from the planet's edge - are made mainly of water ice but are very thin 10m thick - Rings are thought to have formed at different times and in different ways
More energy than expected is emitted because
- gravitational contraction - the right pressures and temperatures in its hydrogen ocean to support helium rain
Both Jupiter and Saturn
- have liquid metallic hydrogen in their interior -have rings - emit more energy than they absorb from the Sun - rotate very rapidly
Jupiter's Belts & Zones
- horizontally banded atmospheric structures - dark belts = high pressure material that has risen - lighter belts = lower pressure material dropping down - heat-driven convection
Saturn's atmosphere contains
- hydrogen - helium - increased amounts of methane and ammonia
Uranus & Neptune
- large amounts of light elements with low densities - both have Earth-sized rocky cores - above each core is a slush layer of ices of methane & ammonia - Magnetic fields attributed to ammonia slush
Ganymede
- largest of Jupiter's moons - lower density suggests rocky core with ice-rock mantle - appears to have shallow sub-surface sea - craters - water-rich flows streamed - unknown if it is geologically active
Titan has
- low density - atmosphere composed mainly of nitrogen and a wide range of hydrocarbon compounds - Lakes of of liquid methane and methane rain observed
Io
- most geologically active world - due to its proximity to Jupiter - volcanism due to tidal heating --> friction - surface continually repaved by lava
Jupiter's Auroras
- observed at Jovian Poles - images captured by HST - larger & more energetic b/c increased field strength & magnetosphere
Saturn rotation
- once every 10.6 hours - differential
Jupiter's Atmosphere (top to bottom)
- pure hydrogen - ammonia droplet clouds - ammonia sulfide clouds - water clouds
Jupiter's magnetic field is caused by?
- quickly rotating thick layer of liquid, metallic hydrogen source of planet's dynamo --> strong magnetic field (20,000x Earth's)
Saturn's structure is?
- same as Jupiter's a dense core, metallic hydrogen, and molecular hydrogen.
Jupiter's Interior
- similar to the Sun's - 75% hydrogen, 25% helium, traces of heavier elements - differential rotation - liquid ocean of molecular hydrogen - metallic hydrogen - metallic and rocky core (15x mass of Earth) - tempt at core is 30,000 K
Europa
- slightly smaller than Earth's moon - high density which suggests differentiation - very reflective surface --> young water ice - moving "icebergs" on surface - liquid water ocean 100 km deep --> good candidate for life
Io Torus
- thick, relatively cool ring of plasma circling Jupiter
Callisto
- tidally locked due to Jupiter's large gravitational field - geologically inactive - Due to increased distance from Jupiter (low temperatures), Callisto does not appear to have differentiated to produce a core --> water ice mixed with silicates -surface composed of dark ice shattered by craters - Under surface ice is a layer of liquid water 10 to 100 km thick.
The rings of Neptune
- were confirmed by Voyager 2 in 1989 - number five, three narrow and two diffuse - often appear as clumpy ring arcs, rather than complete and symmetrical
High pressures at cores causes?
-hydrogen to exist in its metallic state (acts like a metal) -high temperatures
Beyond the ice line....
-planets accumulate lots of ice and other frozen compounds of hydrogen -sunlight still spurs chemical reactions
Jovian Giants Internal Structure
-rocky metallic core -low masses due to gaseous makeup
Fast rotation rates cause ________ & __________
-s trong magnetic fields - flattened planets (esp. Saturn)
Jovian Giants also have very _________________ rotation rates which cause ______________________________
1) very fast 2) very strong atmospheric currents
Saturn's winds can reach speeds up to?
1,800 km/hr
The energy emitted is more than _____ times what it receives from the Sun.
2.5
Saturn is the _____ largest planet in the solar system
2nd
How many rings does Jupiter have?
4
Saturn has how many known moons?
62
You have recently observed a moon and notice that its orbital plane is highly inclined and its orbit is retrograde. You would most likely classify this moon as
An irregular satellite
_________ used longer waves to see beyond the haze
Cassini
Who first discovered Saturn's rings?
Christian Huygens
The surface of which Jovian moon most resembles the pack ice of the Arctic Ocean?
Europa
Who first observed Saturn?
Galileo
In 1989, Neptune was found to have a huge storm named the
Great Dark Spot
Gas Giants
Jupiter & Saturn
Gas giants like Saturn maintain strong magnetic fields because of the Dynamo Effect created by what material?
Metallic hydrogen
Which moon generates a 2:1 orbital resonance with the Cassini Division?
Mimas
Which moon of Uranus displays the widest range of surface terrains, suggesting some sort of large scale geological or catastrophic activity?
Miranda
Densities (largest to smallest)
Neptune, Jupiter, Uranus, Saturn
Orbital Periods (longest to shortest)
Neptune, Uranus, Saturn, Jupiter
A possible ring was discovered on Jupiter by?
New Horizons (Himalia Ring)
What planet can you observe a strange six-sided, hexagon-shaped storm at the north pole (Cassini)
Saturn
Which of the following has the LOWEST mean density?
Saturn
Our perspective of Saturn changes through our yearly orbit because?
Saturn maintains its tilt relative to its plane of orbit on its trip around the Sun.
Galilean Moons refer to?
The four largest moons of Jupiter: - Io, Europa, Ganymede, Callisto (increasing distance from Jupiter) - densities decrease as they get further from Jupiter - all are tidally locked
Why are the rings of Saturn so bright?
The ice particles are very reflective
Saturn's largest moon is?
Titan
Which moon in the solar system shows a DENSE atmosphere?
Titan
Which of these moons are most exciting to exobiologists?
Titan and Europa
This is the darkest Uranian moon, with its only notable feature being a large, bright spot on its Northern Hemisphere.
Umbriel
Adams and Leverrier both predicted the position of Neptune based on its effects on
Uranus
William Herschel thought he had found a comet when he spotted the green disk of
Uranus
Ice Giants
Uranus & Neptune
The magnetic field of which two planets are most unusual?
Uranus and Neptune
Rotation Period (longest to shortest)
Uranus, Neptune, Saturn, Jupiter
Arrange the following planets by rotation period, longest to shortest.
Venus, Mercury, Mars, Uranus, Saturn
Saturn's oblateness causes
a reduction in Saturn's overall density by combating the inward pull of gravity
Triton is the only known natural, large satellite that has
a retrograde orbit
Uranus' and Neptune's appearance is so dull compared to Jupiter's because
actually they are quite dynamic and varied but it is difficult to see past the obscuring haze
The rings of Saturn show a variety of brightness, which can be an indication of the
age of the ice particles
The magnetic fields of Uranus and Neptune are attributed to
ammonia slush
What other object has been found to have rings?
asteroid named Chariklo
What do Earth's and Jupiter's magnetic field share?
auroral displays at poles
Medium and large moons would be torn apart within the Roche Limit
because of the gravitational variation over these bodies results in large tidal forces
Ice Line
beyond 4.5 AU from the Sun, defined as where ice is a stable form of water.
How was the first ring of Jupiter discovered?
by Voyager I as it passed Jupiter
Uranus and Neptune present a quandary to astronomers because
composition and magnetic field orientation
Clouds in Saturn's atmosphere are similar to Jupiter's but are?
deeper within the atmosphere
The Roche Limit is defined as the critical
distance from a planet, inside of which a moon can be tidally destroyed
What supplies Jupiter's rings?
dust particles from small moons
Saturn's rings are EDGE-ON, so they would vanish when Saturn is at
equinox
A stable orbit can only contain one moon.
false
Jupiter and Saturn are both within the ice line while Uranus and Neptune lie past it, so that is why Jupiter and Saturn are Gas Giants and Uranus and Neptune are Ice Giants.
false
One can use higher frequencies like IR to probe deeper into obscuring haze layers
false
True or false: Saturn's surface is smoother than Jupiter's
false
Irregular satellites are generally
farther from Saturn and are in highly inclined orbits. They can have prograde or retrograde orbits.
Saturn radiates even more excess energy than Jupiter because
helium rain gives off heat as it falls toward Saturn's center
Saturn primarily consists of?
hydrogen & helium
Uranus & Neptune layers (inner --> out)
ice/rock core --> mantle of water, ammonia, methane ices --> hydrogen, helium, methane gases --> surface
Which of these is TRUE about the seasons on Uranus?
its strange tilt produces extreme seasonal variations
Source of Jupiter's large magnetic field
metallic hydrogen swirling in its interior
The two outer Jovian planets appear bluish because
methane absorbs red ligh
Shepherd satellites are defined as
moons that confine a narrow ring
Saturn emits ______ energy than it receives from the sun
more
Uranus's axial tilt is 98 degrees, leading to what
most dramatic seasons possible
How is Saturn's density compared to Jupiter's?
much lower
The tenuous atmosphere on Triton is composed primarily of
nitrogen
Due to its rotation, Saturn is very
oblate
Equilibrium temp (Hottest ---> coolest)
planet order from the sun
Jupiter & Saturn are composed of?
primarily hydrogen & helium
Uranus & Neptune are composed of?
primarily hydrogen compounds -methane -water -ammonia
Regular satellites generally have
prograde orbits stay close to plane of Saturn's equator
Jupiter and the other Jovian planets are noticeably more oblate (i.e. football shaped) because they have
rapid rotation and a fluid interior
Neptune's axial tilt is 28 degrees, which is
similar to Earth's
Suppose you have detected a new planet in our solar system with an atmosphere with considerable amounts of hydrogen and helium, small amounts of methane and very small amounts of ammonia
somewhere between the orbits of Uranus and Neptune
Saturn has a strong magnetic field due to?
the interaction of its layer of metallic hydrogen and its fast rotation rate.
The excess heat produced by all four giant planets is attributed to
the slow continual contraction of each planet
Jovian Giants formed beyond?
the snow line (ice line)
Chariklo and Haumea present a challenge to astronomers because
they are very small objects but they do have ring systems
Metallic hydrogen is notably absent in the interior structure of Uranus and Neptune because
they do not have sufficient interior pressures and temperatures to drive hydrogen into the metallic state
What is thought to cause Io's volcanism?
tidal stress from Jupiter and Europa
