Lecture 9 - Jovian Planets and Asteroids Flashcards
the moon is geologically ______. why (3)?
dead
- has many craters (not erased by erosion/volcanic activity)
- little tectonic activity
- no magnetic field
why are both mercury and the moon geologically dead? what is not a reason why?
both small so they cooled off faster
they DID undergo significant impacts but this would have produced a lot of heat, so it is not a reason why
what element does Sun produce? does it populate the solar system?
He
does not populate the solar system
what occurs in the earth’s core?
earth’s core manufactures new elements via nuclear fusion to make lighter elements
why do we know H and He makes up most of the mass of the solar system?
bc the sun makes up most of the solar system and it makes H and He
what is the most massive planet in the solar system?
how many times larger is Jupiter than Earth?
jupiter makes up __% of total mass of all planets
jupiter
317 Earth masses
makes up 70% of total mass of all planets
how many times larger is Jupiter’s radius than Earth?
Jupiter is large –> 11 Earth radii
what is the orbital period of Jupiter?
11.8 years @ 5.2 AU
is Jupiter’s density higher or lower than terrestrial planets? give numbers
lower
1.3 g/cm^3 vs 5.6 g/cm^3
Why is Jupiter considered to be a failed star?
Mainly H, some He
similar to star but without fusion (only diff from the sun)
what is the period of Jupiter’s rotation? is this fast or slow?
period is 9.6h –> fast
describe the surface of Jupiter, how does it change as you go downward??
no surface –> gas gets denser and liquifies as you go downward
how do we see the atmospheric effects/weather on Jupiter?
colours, patterns, and other features
is Jupiter in motion or stationary?
in motion
what is the energy source of Jupiter?
GRAVITATIONAL CONTRACTION –> oscillates btwn contraction and relaxation
where do Jupiter’s colours come from? (3)
sulphur, phosphorous, organic molecules
what are the belts of Jupiter caused by?
what are the zones of Jupiter caused by?
belts –> dark regions, falling gas
zones –> light regions, rising gas
what is the GREAT RED SPOT?
how do its clouds move?
how long has it existed? who discovered it?
how big is it compared to Earth?
storm system, like a hurricane
clouds rotate every 6 days
existed for >300 years, first seen by Cassini
3x size of Earth
how do we know about Jupiter’s interior structure? what is unknown?
inferred from known gas properties and gravity
little is known about the core, unsure if molten or solid
what is present in Jupiter’s interior structure around the core?
what does it act as?
why can it do this?
what does this allow?
liquid metallic hydrogen
acts as a conductor
H not normally a conductor but its electrons are moving more freely
conduction allows production of magnetic fields
what is Jupiter’s core made of? why?
heavy metals –> must have swept up heavy metals
what are 8 similarities btwn Saturn and Jupiter?
- massive
- large in size
- low density compared to terrestrial planets
- similar inferred interior structure
- fast rotation
- substantial magnetic field
- visible zones, belts
- mainly H atmosphere
why are zones and belts less visible on saturn vs jupiter?
Saturn has lower mass so its atmosphere is less compressed than Jupiter
what are Saturn’s rings made of?
what plane is it in?
what is its rotation axis?
can we see ring edge-on?
made of millions of highly reflective ice-covered rocks (cm-m)
in Saturn’s equatorial plane –> same plane it rotates with
rotation axis is 27deg to ecliptic
can see rings from diff perspectives but not edge-on bc very thin (2km)
why are Jovian planets smaller when they are further from the sun?
less particles are available to sweep up for planet formation
describe the structure of uranus and neptune
metallic core with layer of (1) metallic gas (2) liquid gas then (3) actual gas on surface
what are the 4 types of Jovian planet moons?
- Tiny “moons” near rings
- Small moons on outskirts of rings
- Large moons at intermediate distances
- Small moons on outskirts of gravitational sphere of influence
describe tiny “moons” near rings
made of ring material
describe small moons on outskirts of rings
“feed” the rings
describe large moons at intermediate distances
interesting geologies, “world-class”
describe small moons on outskirts of gravitational sphere of influence
captured, often retrograde orbits
how many moons does Jupiter have?
Saturn?
Uranus?
Neptune?
Jupiter: 67 (4 Galilean)
Saturn: 62
Uranus: 27
Neptune: 14
why do Jovian planets have more moons than Terrestrial planets?
there are more moons to capture in the outer solar system and Jovian planets are more massive
which of Jupiter’s moons has a volcano?
Io
what is the name of Io’s volcano?
what is its volcanic plume made of?
why is it special?
what happens to hot molten rock?
Called Pillan Patera
Volcanic plume is sulfurous emissions
Most volcanic activity of anything in solar system, seen in every image of Io
Hot molten rock leaks out
why does Io have a slightly elliptical orbit?
combined tugs from other Galilean moons when they line up has pulled it into an elliptical orbit (all 3 Galilean moons get elliptical orbit this way)
describe Io tidal heating
tidal heating means that Io is the most ____________ in the solar system
each orbit, tidal force causes the crust to rise and fall by 100m which causes friction that heats Io
tidal heating means that Io is the most geologically active body in the solar system
what are the 3 Galilean moons in order of distance from Jupiter?
- Io
- Europa
- Ganymede
describe the size of Europa vs Io
Europa is same size but half the mass
what process occurs on Europa? why?
tidal heating
surface is covered by water ice which has many cracks and folds due to tidal stress
why could life exist on Europa?
water ice on surface suggests liquid ocean of water below ice layer that is a few km thick
what is unique about Europa’s surface?
smoothest surface of Galilean moons
what is the largest moon in the solar system?
describe geological evidence on this moon
Ganymede
clear evidence of geological activity –> tidal heating + heat from radioactive decay
what type of object are comets, asteroids, and meteors?
planetesimals
how much of the mass of solar system do comets/asteroids/meteors make up?
0.0001 of the mass
why are comets/asteroids/meteors unimportant? why are they important?
unimportant in solar system but important for history of space observation
what do comets/asteroids/meteors provide clues for?
could provide clues for formation/evolution of solar system and geological events that released things into atmosphere
- what are asteroids?
- how do they travel
- where are they mainly found?
- how many are catalogued?
- what is their general shape?
- are they detectable without a telescope?
- asteroids = ROCKY/METALLIC objects
- travel in circular orbits around sun
- found mainly in asteroid belt btwn Mars and Jupiter
- 200,000 catalogued
- generally irregularly shaped
- not detectable with naked eye
- do comets enter the inner solar system?
- what are the parts of a comet?
- what is a comet made of?
- how large is a comet?
- what are the 2 types of tails?
- what laws do they follow?
- where do they come from?
- comets occasionally enter the inner solar system
- head and tail
- head = solid ice nucleus of water, methane, ammonia, CO2 and the rest is gas + dust
- 1-20km big
- Ion tail, Dust tail
- follow Kepler’s laws
- come from outer solar system
what is the Ion Tail of a comet?
points away from the sun and charged particles are forced away by solar magnetic field
what is the Dust Tail of a comet?
curves away a bit from an ion tail and dust is released and continues orbit but curves due to radiation pressure from sun
how big can comet tails be?
1 AU
How do comets follow Kepler’s laws? what does this imply?
comets orbit in ellipses with the sun at 1 focus and the comets sweep out equal areas in equal times, therefore very fast when it approaches the sun
this implies that comets spend most of their time far away and we only see a small fraction
what did Jan Oort propose?
how is this observed?
proposed the spherical swarm of comet nuclei beyond pluto called the OORT CLOUD
never directly observed –> just infer its presence
what is the Oort cloud evidence for? (3)
- most comets only come around 1x
- come from any direction
- many are unseen
where did the Oort cloud come from?
what are the periods of comets in Oort cloud?
how many AU?
flung out by Jupiter’s gravity
10-60 million year periods
50,000 - 150,000 AU
What is unique about Halley’s comet?
it returns!
where do comets originate from? how do we know?
originate from much closer than Oort cloud
we know based on orbital properties
- what is the Kuiper Belt?
- how big is it?
- can we directly observe them?
- how are they located relative to the solar system and what does this indicate?
- 2nd group of comets beyond Neptune and Pluto
- 30-100AU
- dozens have been directly observed
- lie mainly in the plane of the solar system, indicating that they remain from the formation of the solar system
describe meteor showers
remains of comets travel across the sky as a quick streak of light, leaving its history in its tail
