Astro Quiz Q's
How do other planetary systems differ from ours?
Very large planets orbiting very close to their stars - could not always be the case, but these are the easiest for us to see and detect
Presence of moon for complex life on earth
moon stabilizes obliquity of earth's axis over time
Relative ages are based on _____
"Stratigraphy" Old surfaces sit below young surfaces & Crater counting
Why is Jupiter so large?
- what you are made of strongly depends upon what can condense (be solid) where you are made - Outside of the Snow Line ices can condense to become planetary building blocks - Ices are more abundant than rock outside of the Snow Line so you can make things big and do it quickly there ACCRETION TIME DEPENDS STRONGLY ON DISTANCE FROM THE SUN, 3 AU is where Jupiter formed.
Characteristics of the asteroid belt
-Abnormally shaped, -do not make the threshold for round bodies because they are too small, -they are also cratered. -Many asteroids are probably "rubble piles" because they are repeatedly hit. -Can't spin too fast or they will fall apart. -Some have moons too. -About ten times the space of earth to moon between each asteroid.
Moment of inertia of a uniform sphere
0.4
Distance between sun & earth
1 AU
Room pressure
1 atm
Density of water
1 g/cm^3
How would you go about detecting planets around other stars?
1) Direct Imaging- we see the planet because our sun reflects light off of it, difficult because our sun emits so much light, and because the other sun has light too. 2) Radial velocity- measure wavelength of the star when it wobbles towards (red wavelength) and away (blue wavelength) from us, the Doppler effect
Five stages of planetary revolution
1. Origin 2. Differentiation 3. Late heavy bombardment 4. Geological activity 5. The big chill
Room temperature
20 C 70 F
How would you go about detecting planets around other stars? Pt. 2
3) transit- measures the change in light from a star when a planet passes in front of it, dimming the total amount light coming from the star 4) Microlensing- lens star and source star are aligned, a planet around the lens star distorts light from the source star
What is the reciprocal of 3/8?
8/3
Sun
99% of the solar systems mass Solar flares send high-energy particles into the SS that kill biology.
Volatility
A more volatile substance evaporates at a lower temperature than a less volatile (more refractory) one.
Why would you expect to find planets around other stars?
All stars form the same. Planets are a natural consequence of star formation.
Why can't liquid exist on present Mars?
Atmosphere is too thin
Where are most asteroids located?
Between Mars and Jupiter= the Asteroid belt.
What do I mean if I say that a material is very volatile?
It takes very little energy to cause the material to change state
The amount of heat inside a world is constantly _________ over time as the fuel gets used up
Decreasing
Absolute ages
Determined from hard samples
Why do gas giant planet atmosphere's look different?
Different composition - What causes the different color of the clouds? Trace gasses (ices) are responsible for the diversity of colors
What are the biases of the various techniques?
Direct imaging: only can see planets that reflect the light of our sun Radial velocity: we find the most with this because you can use it on every star that is found Transit: only see planets that cross between us and the star, this means we must be on a plane with the planet and its star Microlensing: we can only use it when the lens star and the source star are aligned, takes a long time to find two aligned stars
Moons atmosphere
Doesn't have one
Describe how you can determine the size (radius) of a world if you know its gravity and mass.
F=M/R2
What is the origin of the asteroid belt?
Formed during the solar system formation, protostellar disk of material rocks that never accumulated into a planet, -there is not enough mass there to form a planet and their chemical differences disproves the explanation that they were once single planet that got broken up.
Limiting factor on height of a mountain
Gravity
A world with a density of 5.2 g/cm3 would be composed of
Half rock, half iron
Most common elements
ICE Rock Iron
Densities you should know.
Ice = 1 g/cm3 Rock = 3 g/cm3 Iron = 7.9 g/cm3
What is the most common geological feature on the surfaces of Dead worlds?
Impact Craters
Moment of Inertia Factor (K)
It's a number- how things are distributed on the inside an object If heaviest matter is concentrated in the center- the #<.40
Io
Jupiter 2:1 resonance with Jupiter This causes tidal heating-consistently being squished. eccentric orbit invokes tidal kneading heating causes molten interior-magma ocean constantly resurfaced by sheild volcanoes that are gyser like Cannot sustain life due to Jupiters magnetic field. Sulfer volcanoes and surface
Euopa
Jupiter rock inside Jupiter's snow line 2:1 resonance with Io Tidal kneading reduced due to Io cracked surface allows the water ocean underneith to come through the icy surface Largest ocean in the solar sytem
How do we know that Jupiter and Saturn have magnetic fields?
Jupiter and Saturn are noisy in the radio - sparks and snaps can be detected in noise
Why does Jupiter's magnetic field make it a hazardous place (for life)?
Jupiter has massive Van Allen Belts. It is too strong. Strips material form Io and Europa and brings it to the pole of Jupiter.
What is the Oort Cloud and how did it form?
Jupiter kicked out all of the Oort Cloud objects over time.
Equation for kinetic energy
K.E= 1/2 Mass Velocity^2
How did the Kuiper Belt form?
KBOs are the leftover materials from the formation of the Solar System. KBOs haven't had enough time to accrete into a planet!
How could you determine if there was life on some of these planets?
Look for a gas that is completely out of equilibrium because biology messes with secondary atmospheres.
Large worlds geographically active longer than small worlds because ___
Lose energy at a slower rate
How do we get from a homogeneous mixture of materials to the Solar System we see today?
Lots of gas and dust available in spiral arms for star and planet formation - Stars form from giant molecular clouds. Dense regions spin and collapse into disks of material. Star forms in the center - planets orbit with low inclinations - a natural consequence! - Massive star death creates the late stage elements -Iron Meteorites - Best evidence for our SS forming from the collapse driven by a nearby Stellar Nebula explosion
Why does Earth's magnetic field make it a safe place to live?
Magnetic field also traps high-energy particles in regions called the Van Allen Belts (swaths of radiation). High energy particles from the sun are deflected by earth's magnetic field High-energy particles damage cells faster than they can repair (this does not happen because of the protection of the magnetic field)
Where do meteorites come from?
Mars, and the Moon from LHB and from the asteroid belt.
Asteroid Belt
Material that never formed into a planet Extremely spaced out Jupiter kicks in Asteroids towards the planets (Meteorites)
What are the interiors of giant planets like?
Molten interior They have very strong magnetic fields. -These require Conducting material (must have free electrons), -Internal Energy Source (need to conducting material to be molten), -Moderately fast rotation (need to move the electrons, convect the fluid).
Moon is made up of...
Mostly rock
Cumulative crater density
N (10) The total number of craters equal to or larger than 10 lm per million square km
Triton
Neptune Rock/Ice icy surface Cyro-volcanism retrograde orbit captured Equatorial regions show dry lake beds. Nitrogen ice on the surfaces liquid underneath is heated by the sun, causing volcanism. thin atmosphere
How has its extreme size dictated events throughout the history of the Solar System?
Nice Model, Form big planets THEN move inward with the help of resonance. -Jupiter moves toward Sun (loses energy from interactions) and scatters material everywhere in the Solar System~3.8Byrs ago, LATE HEAVY BOMBARDMENT Nice Model: - scattered in: LHB Scattered out: Oort cloud Left over: Kuiper Belt
Mercury
No atmosphere huge iron core iron and rock
No atmosphere=
No pressure
Crater density
Number of craters (N) larger than a certain size (D)
Radioactive decay is a _____ process
One-way
Endogenetic source
Originating internally Energy from radioactive decay of elements
What do the Kuiper Belt and Oort Cloud have to do with comets?
Outside of the snow line, comets are icy, both locations are due to Jupiter's resonances, and Jupiter tosses comets into the inner solar system. Oort cloud is long period comets and Kuiper belt is short period comets
Carbonaceous chondrites
Primitive meteorites that are representative of the composition of the nebular cloud that condensed to form our solar system
Crater population
Relative number of different sized craters
R-Plot
Relative number of different sized craters
I said that the surface of Saturn's moon Rhea is about 3.8 billion years old because it has about the same crater density as the highlands of the Earth's Moon. Why might this statement be completely wrong.
Rhea may not have been hit by the same population of impactors as the Moon
Saturn
Rings! Roche limit Titan and Enceladus
Impact breccia
Rock composed of broken fragments of minerals or rock cemented together
Basalt
Rock formed from the cooling of lava at or near the surface
Enceladus
Saturn Ice but a little rock rarely round(almost too small) brightest planet Cyro volcanism Ice on top, sun rays get trapped underneath and cause the surface to blow this volcansim causes the E ring outside of the roche limit Geo activity is only on south pole Tidal heating
Titon
Saturn Satellite with atmosphere Methane cycle Petrochemical lakes methane easily dissociated by sunlight replenished by lakes
Regular satellite properties
Size: - Large (Earth's Moon Size) Formation: - Co-Accretion (not like the Moon!- like Solar System) Orbits: - Prograde & Synchronous (sameside faces planet) - Low eccentricity - nearlycircular - Low Inclination - orbit above theplanet equator - Close to the planet Composition: - Ice & Rock (formed outside of Snow Line) Some (not all) are heavily cratered
Irregular satellite properties
Size: - Small (typical asteroid sizes) Formation: - Capture (captured asteroids) Orbits: - Prograde and Retrograde - High eccentricity - High Inclination - Far from the planet Composition: - Primarily ice (far outside of the Snow Line) --Heavily cratered
Ring Properties
Size: - Very small (cm to m diameters) Formation: - ?? Orbits: - Prograde - Very low eccentricity - nearly circular - Very low Inclination - orbit above the equator - Very, very close to the planet Composition - Mostly Ice (outside of Snow Line)
Mars
Small CO2 atmosphere No magnetic field=no life due to solar flares
Phase of matter depends on...
Temperature & Atmospheric Pressure
Why can't liquid water exist on the present surface of Mars?
The atmosphere is too thin
What is the Roche Limit of a planet?
The closest distance from the center of a planet that a satellite can approach without being pulled apart by the planet's gravitational field. Tidal forces are greater than gravitational forces. Where the ring is, tidal forces keep them from accreting to anything.
Accretion
The collision growth of objects (process) Small objects come together to form larger objects
How are giant planet atmosphere's different than terrestrial planet atmospheres?
They are secondary atmospheres Methane, ammonia, and water while terrestrial atmospheres are CO2, N2, H20 Atmospheres are driven from below(not by the Sun). Terrestrial planets do not have primary atmospheres, because it takes little energy for them to escape and because we are close to the sun they do escape.
Where are meteorites found on earth?
They fall uniformly on earth but we are able to find them in dry stable places but are especially easy to find in Antarctica, not only because of the meteorites dark color against the snow but also the way Antarctica gathers them is one place.
The earth & moon lack volatiles compared to other planets- what does it mean about their past?
They were both heated up in the past
Venus
Thick atmosphere CO2 Modified by wind and geologic activity too hot resurfaced every 0.5 Byrs
Earth
Tidal drag with the moon Moon is gaining energy The moon keeps earth obliquity in check
Saturn's moon Titan is about the same size as the Earth's Moon. Why can Titan retain a thick atmosphere while the Moon can not?
Titan is farther from the Sun than the Moon
Sublimation
Transition from a solid to a gas
Neptune
Triton
Jupiter
Trojan asteroids move with Jupiter Io and Europa-the moons Large magnetic field, strips the surface of satellites, making life not possible 2:1 resonance with Saturn. second largest body in our Solar System. EVERYTHING IS JUPITER'S FAULT has it's own snow line
Jupiter's Fault
Uranus & Neptune, moved and switched position due to dynamical migration & 1:2 resonance with Saturn ▪ Mars small mass ▪ Rise of humans (mammals) after KT event killed dinosaurs ▪ Oort cloud formation from dynamical migration & 1:2 resonance with Saturn ▪ delivery of volatiles and organics from the outer Solar System to the inner, volatile poor planets
A world that has been heated will be depleted of ______ and enhanced in refractory materials
Volatile materials
achondrites
all are highly altered
Moon's K factor
almost homogeneous (.39)
Iron Meteorites
come from iron core of a diff. body
What is Pluto's orbit like?
elliptical and inclined
Unit for density
g/cm^3
The Roche limit for Saturn lies about 2.5 planetary radii away. This distance is:
near the outer edge of the rings
ordinary chondrites
slightly heated
stony-iron meteorites
some rock, some iron. differentiaiton caught in the act
objects in solar system
sun= 99.85% rest planets
Uranus
switched with Neptune during SS formation
albedo
the percentage of sunlight that reflects off a surface
The two most abundant gasses released by volcanism in the inner solar system are
water and carbon dioxide
Why does the density of terrestrial worlds decrease as you move further from the Sun?
what you are made of strongly depends upon what can condense (be solid) where you are made n only rock and iron when formed close to the sun because ice and gases are moved outward (can't stand the heat from the proto-sun). n Overall less material compared to outside the snow line, which has rocks, ices and gases.
age of solar system
~4.5 Byrs
What are resonances and why are they important?
· Resonance is when two orbital bodies periodically exert a gravitational pull on each other · Resonances change orbits - Asteroids do not like to be in resonance with Jupiter - Jupiter is depleting the asteroid belt
