Post midterm ! Flashcards
Protoplanetary disk inside frostline porpotions of materials..
0.2 metal
0.4 rock
1.4 hydrogen compounds
98 helium
Outside frost line porpotion of materials
0.2 metal (solid)
0.4 Rock (solid)
1.4 Hydrogen compounds
98 helium
Tiny small objects stick together to form
planetesimals
Planetesimals are the _____ of what will become planets
seeds
How does a crater form
planetesimal hits surface and vaporizes rock, creating explosion
heavy bombardment period
lots of planetisemals crashing everywhere after planets formed about 4 bil years ago
mercury and moon covered in
craters
LOOK UNDER SURFACE OF PLANET USING
SOUND WAVES
2 types of waves (vibrational travel)
P waves - compression
S waves - side to side
S wave paths
cant go past the liquid in the ball
what is the empty s wave parrt that cant be reached called
s - wave shadow zone
P wave paths
it goes through the liquid ball but everytime it goes through the curve of the line is like reflected
Timing for seismometers at different places depend on
how far and fast the wave traveled
Direction of ——– tell difference between S and P waves
vibrations
S wave on graph is
horizontal (east to west/ north to south)
P wave measured on graph is
verticle
Mercury is estimated from
density + spin rate variations
Venus is estimated from
density
Earth moon mars measured with
seismometers
Why do planets have cores
differentiation: lighter materials like rock float to top, heavier materails like iron sink
Why planet interiors hot:
accretion:
Dominant during formation
Why planet interiors hot:
differentiation:
more dominant earlier
Why planet interiors hot:
radioactive decay:
Dominant source of heat today
Planets cool via
convection
HOW PLANETS COOL step 1
convection:
Hot rock will rise, cool rock sink, hot rot goes surface and release heat
HOW PLANETS COOL step 2
Conduction:
carries the hot rock heat out cuz its thin and rigid
HOW PLANETS COOL step 3
radiation
energy gets radiated to space at surface as infrared light
smaller planets have less —— compared to surface area of a large planet
mass
craters get covered by, what does it indicate
molten lava spewing out and hardening, young surface
are any of earths craters result from heavy bombardement
no
mars has 384343 craters larger than _____km
1
Mares on the moon are
dark spots that used to be craters but got hard lava covered it
Mars has many volcanoes that are
NOT ACTIVE
Small terrestrial planets interior cools… leading to……
rapidly
quickly ending volcanic activity
lack of volcanic activity means no outgassing cuz low gravity allows gas to escape –> no atmosphere
LAck of volcanic activity on small terrestrial planets means
low outgassing, so gas leaves really easily and does not form atmosphere leading to NO EROSION
large terrestrial size and stuff is
opposite of little planet:
Slow cooling
volcanic activity
has atmosphere?
outgassing produces
atmosphere
Temperature changes can put stress on planets crust causing. (2things)
mountains and cracksq
PLate tectonic workings:
Subduction at CONVERGING plates
ocean plates get pushed under continent plates, making the continental plates high (mountain)
PLate tectonic workings:
diverging plates
causes undersea ridges
No erosion likely means
water stopped flowing
Trend in terrestrial planet atmospheres
larger planets have thicker atmospheres
NO h2 in the atmosphere
Higher temperature means what for average speed
faster average speed
higher mass means what for avg speed
slower avg speed
Objects going faster than a planets escape velocity will…..
escape into space
lower mass planets have lower…. soo….
escape velocity, easier to escape
It is easier to escape a —– planet’s gravity
small
low mass gas moves….. so…
faster, easier to escape
Hot gas moves…… so…..
faster, easier to escape
Mercury + Moon escapes velocities are
low
Venus escape velocity is
high
Mars escape velocity is
in the middle (between mercury and venus)
venus, mars, merury, moon escape velocities are all
too low to keep H2
Carbon cycle on earth (why is N2 left as dominant gas)
Co2 in air dissolves in rainwater
water flows into ocean with minerals
Co2 in water reacts with rocks/metals to form CARBONATE ROCKS
carbonate rock is pushed to ocean floor under tectonic plates
volcanos releases small amounts of this co2 back into atmosphere
why doesn’t earth have much CO2
it has water
Co2 levels on earth vary based on
volcanism
biological activity
have ben dropping for the past 50 mil years
The warmer the planet, the more ———– —— is emitted
infrared light
The planet will warm until the absorption of ——— —– and emission of —— —— are balanced
visible light
infrared light
Visible light from the sun shines on planet, some light is ——— and the rest is ——–
reflected (as infrared)
absorbed
Greenhouse effect (think of how blanket works)
“No u”
visible light gets in the atmosphere which is mostly absorbed and the planet gets hot so infrared light is emitted and the greenhouse gasses absorb and remit this back onto surface (blanket)
venus is EXTREMELY hot because
thickass atmosphere, traps lots of heat, greenhouse gas effect
PHOTODISSOCIATION:
– light from sun separates atmospheres’ ——
UV
atoms
PHOTODISSOCIATION:
the separated atoms from the UV light will——– asap after ——— each other
reconnect
refinding
individual atoms are lighter than molecule so……
can escape easier
Solar wind of high energy particles do what to the atoms on mars
knock thema way
define crust
low density rock
core
high density iron/nickel
mantle
medium density rock
Earth’s magnetic field deflect solar wind particles which…
stops the atmosphere from breaking
Asteroids orbit……….. they are not large enough to be…..
the sun
spherical
half an elliptical is called (YELLOW LINE DIVIDING ELLIPSE)
SEMI-MAJOR AXIS
Time of an orbit (period) depends on
semi major axis
Jupiter effects the —— of the asteroids
orbits
Orbits in —— ———— with Jupiter get ———
exact resonance
displaced
The displaced asteroids form —— — along the ring meaning that there are — asteroids
dark bands
no
Largest object in asteroid belt
Ceres
Ceres inside has
liquid brine, icy crust, rocky center
Vesta is —— asteroid
largest
kuiper belt is x times —– than asteroid belt
what does it include
20-200 times more massive than asteroid belt
includes several dwarf planets
where was kuiper belt formed
outside of frost line
Oort cloud
huge spherical cloud of comets
Comets in oort cloud were formed near ——– but kicked out by ———- ———
JUPITER
gravitational interactions
how many objects in oort cloud
trillions
meteorites are
asteroids that hit earth
Outside frost line, — temperature allow ——— planets to include —— molecules like H20m Nh4 and Ch4
low
condensing
volatile
Where are Terrestrial planets formed inside
INSIDE FROST LINEEE
Juno space probe is doing what rn
orbiting jupiter
Jupiter inside
Before impact:
Just after impact:
Present day:
Dense core
dilute core
Well developed dilute core
Hydrogen can turn form gas to liquid to metal if……… who has this?
theres enough pressure
Jupiter has towards the center
Ammonia clouds are what colur
white
What varies as you enter jupiter?
temperature and pressure
Red bands on jupiter are lower——— clouds, which are ———- and brighter
altitude
warmer
White bands on jupiter are higher—- clouds which are ——- therefore emit —— infrared light
altitude
cooler
less
Saturns hexagon has a huge what
hurricane
Saturns rings are over ——km but less than —km thick
260,000
0.1
Neptune and uranus are called ice giants because
they are big with icy and rocky cores
Neptune is
furthest from sun
28 degree tilt
strongest winds
Uranus
coldest planet
thick water + ammondia + methane mantle
who has thick water + ammondia + methane mantle
uranus
very old created surface mostly made of ices, thin brown layer over ice with giant ridge
Iaeptus
one of most reflective object in solar system (HIGH ALBEDO)
enceladus (a saturn moon)
what does high albedo mean
highly reflective surface
Heavily cratered, very porus (40% empty space), made of ice water
HYPERION
When farther from jupiter, tidal forces are
less
When closer to jupiter, tidal forces are
more
The relationship between the tidal forces when close and far away from jupiter causes ——. This is also called —— ——-. This removes ——— out of orbit so it gradually becomes circular
friction
tidal heating
energy
Gravitational tugs by Europa and Ganymede (fellow moons) does what to its fellow moon
Makes IO’s orbit still elliptical
Small moon —— creates the —– gap via what resonance ratio
mimas
huygens
2:1
bascially moons cause what on rings
deflect particles out of that ring within saturns ring
Waves on the disk (saturns ring) also caused by
tiny moon making thin gap
Not all wavelengths of light are allowed to travel….
travel through the atmosphere
On atmospheric absorption graph, 0 means
no light reaches surface
turbulence in earths atmospheres distorts the….
images we see from telescopes
For long exposure and large telescopes, turbulence…
blurs image
HOBBLE telescope
telescope in earths orbit that is above the atmosphere, 5-10x better resolution
How did voyager probes use planets gravity to advantage (think slingshot)
When they lined up, it used each planets gravity to accelerate or slingshot itself to the next
Transfer orbit steps
- start in inner orbit
- engine burn to speed up
- Now in the transfer orbit
- Do a 2nd burn to speed up
- end in outer orbit
when is fuel used during transfer orbit. whats happening when ur not using fuel?
fuel used when you boost in step 2 and 4.
Laying in orbit
Inner solar system uses solar pannels to convert ——-to ——-
sunlight]\
electricity
Outer solar system uses RADIOISOTOPE THERMOELECTRIC GENERATOR TO generate electricity using
radioactive plutonium
Exoplanet means
a planet orbiting star thats not sun
star NAME then “NAME a”, “NAME b”, “NAME c”
Naming system for exoplanets
exoplanets are very faint compared to their
parent star
through a standard microscope, exoplanets are
essentially invis
Exoplanets are hard to see directly beacause
the parent star bright light shining coveres them
Indirect methods
transit method (2969 planets found)
doppler method/radial velocity (863 found)
when one celestial object passes in front of another from our POV it is called
a transit
seeing Venus in front of sun from earth (OUR POV) is example of
transit
Transit method measures the
light curves
transits only occur if the planets orbit happens to be
edge on as viewed from earth
A dip on the transit graph tells us
a planet blocking the brightness of the parent star (EXOPLANET!!!)
the deep dips are ——— and the half way deep dips are ——–
planet transits
eclipses
THE DEEPER THE TRANSIT,….
THE BIGGER THE EXOPLANET
Difference between night and day sides of transits give us
Temperature
Getting exoplanets spectrum
(Star + planet spectrum) - (star spectrum) = Exoplanet spectrum
What is KEPLER
a transit machine
why is kepler useful
the transits it records is much cleaner
Find periodic spacing by
seeing the big dip and finding the half of it, then finding smallest dip and finding the double of that
For multiple planets periodic spacing has a requirement, whats that
planet 2 has to be bigger and block more light
KEPLER HAS SHOWN THAT THERE ARE MANY MORE —– THAN —– EXOPLANETS
SMALL
large
small exoplanet numbers are all HUGE underestimates because
smaller ones are harder to findddd
large exoplanet numbers are also underestimates because
they have long orbital periods so maybe we aren’t observing for long enough to know
weakness of transit
can only see exoplanets edge on
needs continuous monitor
biased towards close-in
only way to find small exoplanets is from space
overal transit method gives us….. of exoplanets
Size
Temp
Periodic spacing
Spectrum
Strengths or transit method
does not need big telescope
can detect very small exoplanets
ONLY way to measure size
atmospheric composition
IF exoplanets have extra moons or rings, we would see
extra very small dips like super small in the original dip
Doppler effect for light:
Spectra
Redshifted lines
moving away (longer wavelength0
Blueshifted lines
Moving closer to us (shorter wavelength)
more severe blue/red shift towards either direction means
speed is faster
Doppler only measures line of sight:
For object moving DIRECTLY away, we measure
all its speed
Doppler only measures line of sight:
For object moving ACCROSS line of sight, we measure
none of its speed
Doppler only measures line of sight:
objects moving diagonally
Only part of its speed
The only part of motion we can measure in all cases of Doppler line of sight measures is called
radial velocity
KEPLERS 1ST LAW OF ORBIT
Planets orbit sun in elliptical , with sun at focus
why is keplers first law wrong
Planets and stars BOTh orbit the center of mass, but stars are so big that they don’t move much
Why don’t stars move much when orbiting centre of mass
they are so massive that usually they are basically/veryclose to the centre of mass
A star wobbling towards and away from us is
What our POV sees when a star is “orbiting” the centre of mass
exoplanet moves in large orbits but cannot be seen
parent star moves in tiny orbits and is bright enough to see
how can doppler affect be applied
using doppler effect to the spectrum of the star to measure the radial velocity (WOBBLE) of the star as it orbits
Doppler method observes the spectrum of the —– NOT the ——
star NOTT
planet
Keplers third law
p^2/m^2 is same for all planets
Most common type of exoplanet found in BOTH search types jupiters
HOT JUPITERS
51 peg b
first exoplanet found, 0.53 AU
half the mass of jupiter, but closer to sun
hot jupiters current thinking
they FORM in outer system, move inward
term for “formed in outer system, move inward”
planetary migration
Hot jupiters are common because
they are easier to find, they make deeper light scale deeps.
Hot jupiters are heavy and close-in meaning for doppler,
they produce large wobble in parent star
Hot jupiters are heavy and close-in meaning for TRANSIT,
they make deep transit in parent star’s light curves.
term for “wobble or transit repeats quick”
Close-in
Hot jupiters dominance is an
observational bias
Is it usually possible to detect inclination of the orbit
nope
we only have a lower limit on true doppler velocity,
we only know the minimum possible mass of exoplanet
WHEN……
when we find an exoplanet via doppler method
If exoplanet als transits, we know it must be orbiting nearly ———-, so we know its actual —— and ——
EDGE ON
mass and size
doppler weakness
neeed big telescope
only measure minumum mass unless we know inclination
only study one star at a time
doppler method strenght
no continuous monitor
works for any orientation (besides face-on)
very good for massive planets in close-in orbits
Combining transit method (size and inclination) and doppler method (mass) gives us
density
dotted lines on graph plots mean
various possible densities
solar system planets on graph plots are what colur
green
selected transiting exoplanets are what colour
red
kepler 11f
same mass as earth but twice the size
kepler 10b size and density
double size of earth
similar density to lead
Angular size of an objet depends on
how big and far away an object is
LIFE IS EVERYWHERE IN UNIVERSE, GETS TRANSPORTED FROM NEW ASTWROUDS
PANSPERMIA
LUFE AROSE ON EAERTH FROM NATURAL PROCESSES, INORGANIC MATERIAL CONVERSIONS
ABIOGENESIS
nutrients (easy)
Energy - sunlight, heat etc (easy)
liquid water (HARD)
requirements for life
Habitable zone
orbits where a terrestrial planet could have liquid water on surface
What are ESI scores
earth similarity index 0-1, based on exoplanets similarity to earth
FERMI PARADOX
optimisitc view of the drake equation
drake equation
of intelligent civilizations =
Nhp x f life x fciv x fnow
