Earth Sci 1086 Final
Where are most asteroids found in the solar system?
"Main asteroid belt" between Mars and Jupiter most others not in the main belt are "potentially hazardous asteroids"
Trojan satellites
-2 packs of asteroids ahead and behind of Jupiter (orbiting the sun) and are also gravitationally bounded to Jupiter which occupy a position called the Langranian points-considered "companions" of Jupiter -major problem is that they don't orbit Jupiter-many think "satellite" implies orbit of the "parent" however Earth has one true Trojan (2010 TH7) and has acquired a short of enhanced Trojan
Explain the 3 levels of cloud formation on Jupiter and Saturn. On which planet are the clouds higher in the atmosphere and why?
-3 layers depending on temperatures at which various compounds condense -upper layer, 2nd layer: ammonia sulphide, inner most layer is water clouds -Jupiter's clouds are higher as the temperatures to form clouds are found deeper within Saturn's atmosphere
What are 3 principles in comparative planetology?
-First, a body's composition depends on the temperature of the material from which it formed. This is illustrated by the prevalence of ice as a building material in the outer solar system where sunlight is weak -The second principle is that cratering can tell us the age of a hard surface -Finally we will see that internal heat has a powerful influence over the geology of these larger satellites
How did the Cassini Huygens spacecraft get enough energy to reach Saturn's orbit?
-it is dependent on gravity assists from other solar bodies and a plutonium nuclear reactors fuel cell ---this is necessary b/c it's exploring too far from the sun to use solar power -looped around the Sun twice, on the first loop getting close to Venus in its solar orbit where it 'stole' some of the planets orbital momentum -1st spacecraft to explore Saturn from orbit
Saturn and Jupiter are similar in that there is no clear division between the atmosphere and the surface of the planet. Why is this?
-there is a slow gradual change from gaseous atmosphere to liquid planet -does not have a surface in the same as as earth -composition of Saturn's atmosphere broadly reflects the composition of saturns interior ---about 91% hydrogen, 6% helium and the rest consists of nitrogen, oxygen, carbon and few compounds including water, ammonia, methane -atmosphere contains belt zone circulation, zones are higher clouds formed by rising gas and belts are lower clouds formed by sinking gas, the clouds are not very distinct on Saturn -Saturn's atmosphere is much colder than Jupiter's (Saturn is also twice as far from the Sun so this is expected)
How is the light of a fireball formed? Why do the colours change?
2 mechanisms -burning of the solid body itself -the incandescence of the atmosphere immediately around the burning mass colours derive from 2 sources: -composition of the vaporizing material -composition of the luminous air surrounding the hot meteoroid typically, will turn from brilliant white to bright red immediately before it is extinguished atmospheric gases glow--fireball appears much larger and closer than it really is
What are the 2 main components of Saturn's atmosphere?
91% hydrogen, 6% helium
Definition of a gas giant planet
A large, low-density planet composed primarily of hydrogen, helium, methane, and ammonia in either gaseous or liquid state
How can asteroids be classified using albedo and spectral analyses?
Albedo: proportion of light reflected from an object ranging from 0( perfectly black) to 1 (perfectly reflecting) an object with lots of metal showing would be highly reflecting while one composed of carbon would have a very low albedo we can use spectrometers to break down the reflected light into a whole spectrum, which tells us which minerals are reflecting light in addition to simple albedo numbers
What are the common features shared by gas giants?
All have atmospheres of H or He (more H than He) Jupiter and Saturn: boundary between atmosphere and body of planet is gradual (from gas to liquid) Uranus and Neptune: sharp bounding surface between gas and liquid all have hot, rocky cores but are a mix of elements in solid state all surrounded by rings and natural satellites all rotate rapidly--strong atmospheric winds producing cloud bands parallel to equators ----Jupiter rotates faster-most prominent bands
What size of an impactor could cause global effects on Earth?
An asteroid lager than 1 km in diameter
Types of NEAs
Atens, Apollos, Amors
Within the stones category, what is the difference between chondrites and achondrites?
CHONDRITES: aggregates of "cosmic sediment" that have never been altered nor melted since first compressed together--poorly blended aggregates of different materials: nicely rounded chondrites, irregularly shaped inclusions of various compounds, shiny grains of metal alloys and metal sulfides, and a dark fine grained matrix--4.56 B years old (most)--most common meteorites ACHONDRITES: igneous rocks that have been at least partially melted and recrystalized
4 Galilean satellites orbiting Jupiter
Callisto, Ganymede, Europa, Io
Explain how the dark belts and bright zones form in Jupiter's atmosphere
DARK BELTS: regions of descending gas BRIGHT ZONES: regions or rising gas temperature in belt is higher than zone, zones have higher pressure of rising gas that cools as its rises and forms clounds, belts have low pressure with sinking gas and lower clouds belts and zones are highly stable-although colour and brightness change, they have not changed position
Why are some asteroids metallic while others are not?
During differentation, their interior melts and when broken apart layers of rock may be exposed--if just outer layers are broken, we may see a variety of rock types exposed, however if all the outer rock layers are stripped away, we are left with just the metallic core
What is an ASTEROID FAMILY? When 2 asteroids of unequal size collide, will the fragments come from the larger body or the smaller one?
FAMILY: breakup of an asteroid into a collection of fragments-resulting in similar orbital characteristics When 2 asteroids collide, only one asteroid (the larger body) forms the majority of observable fragments resulting from the collision
What is the difference between a find and a fall?
FIND: a meteorite where you more or less stumble across it and have no information of when it got there FALL: a meteorite whose entry through the atmosphere was witnessed, and someone has recovered a piece/all of the object
Jupiter is primarily composed of hydrogen in various states. Describe the structure of the planet. Does the liquid hydrogen ocean have a surface?
From inside out: -core of rock, metals, and hyrdrogen compunds -metallic hydrogen -liquid hydrogen -gaseous hydrogen -cloud tops below the clouds, lies the largest ocean in the solar system, which has no surface and no waves
What is the difference between irons, stony irons, and stones? What is the most commonly found on Earth?
IRONS: consist mainly of iron and nickle metal alloys STONY IRONS: near 50-50 mix of the same metal alloys and non-metallic silicate rocide meteoroid and that looks like ordinary "stone" STONES: almost entirely the latter material; stones made up 93% of all known meteorites
What is the difference between an achondrite and a primitive achondrite?
If a fragment is the product of crystallization from a magma, we call it an achondrite--subdivided based on chemical compostion If a fragment is a chunk of the residual product (material left being that didn't melt), we call it a primitive achondrite
How do we know that it is hot? Why does it have a high heat flow (what is the internal heat engine?)
Infrared observations show that Jupiter emits about 1.7x as much energy as it receives from the sun so it must be very hot inside to have so much heat emitting into space heat is not decay of radioactive elements within the planet-that must be occuring, but not nearly at the rate necessary to produce the recording temperatures; nor is it nuclear fusion INTERNAL HEAT ENGINE: source of Jupiter's excess energy is the slow compaction of the planet (atoms of hydrogen and helium move as gravity slowly pulls them into a more compact configuration, which generates heat)
How do we know that Jupiter is big?
It looks big--4th brightest object in the sky, computing diameter, its 11x Earth Its satellites race around it and don't fly off --Jupiter has to be a massive world to hold onto such a rapidly moving satellite Io-orbits Jupiter in less than 2 days --IO: most volcanically active body in the solar system, EUROPA: significant liquid water ocean beneath surfaces, GANYMEDE: water 'slush' ocean beneath a solid ice cover, CALLISTO: body that never been chemically differentiated (all 4 known as Galilean satellites)
What did we learn by watching the Shoemaker-Levy 9 comet impacting Jupiter?
It passed very close to the planet and was pulled into at least 21 pieces that looped out away from Jupiter in long elliptical orbits fragments weren't that big and hit Jupiter at speed of 60 km/s impacts occurred just over Jupiter's horizon-seen from Earth First, atronomers used impacts as probes of Jupiter's atmosphere--created models of a high velocity projectile penetrating into Jupiter's upper atmosphere-by comparing observed impacts, were able to fine-tune the models to better represent Jupiter's atmosphere-method of comparing models allowed a better understanding of Jupiter's atmosphere second, it reminds us that planets are hit by large objects
Why is Saturn less dense than Jupiter?
Jupiter and Saturn contain the same amount of matter, but Jupiter is much more compact (higher density)
What are Trojan asteroids?
Jupiter ushered 2 groups of asteroids within its own orbits, which have become trapped in the Langranian points along its orbit--cosmic sink holes (langrangian points) have trapped chunks of debris
What are the four gas giants in our planet?
Jupiter, Saturn, Uranus, Neptune
Explain how a meteoroid's mass and velocity affects its momentum and kinetic energy
MOMENTUM: product of a body's mass, the amount of material it contains, and its speed or velocity the more mass the body has or the faster it is travelling, the greater the force necessary to change its state of motion KINETIC ENERGY: energy associated with motion kinetic energy increases exponentially with velocity (doubling the mass, doubles the kinetic energy, while doubling the velocity squares the energy) the greater a meteoroid's mass and velocity, the greater its kinetic energy velocity is a more important factor than mass (must be an enourmous mass)
Do NEAR EARTH OBJECTS (NEOs) have circular or elliptical orbits?
NEOs all follow highly elliptical orbits, and are subdivided into categories according to the dimensions of their orbits
What techniques do we use to analyse a meteorite? What can we learn from these tests?
PETROGRAPHIC MICROSCOPE: mount a very thin slice of a rock on a glass side and study it ---every mineral has optical properties, so we know exact compositions of rock, and how minerals relate texturally ELECTRON MICROPROBE: uses a tiny beam of electron to impact micron-sized volumes of the sample and tell us what elements are present in the value and at what proportions MASS SPECTROMETER: measures amounts of selective radioactive isotopes in the sample--isotopes breakdown at fixed rates-use them as "clocks" ----equations relating amount of a parent isotope to the amount of the isotope that it breaks down to form (daughter) and the time since it began
Give an example of the kinds of features the spacecraft DAWN has observed on large asteroids
Produced images of the surface of VESTA (the most thorougly observed asteroid), revealing its complex history, crustal mineralology, and morphology revealed VESTA had a metal rich core, tallest maoutain is bigger than the largest mountain on Earth Went to Ceres, and found the presence of highly reflective spots within craters
What are 3 classifications of satellites? Compare the characteristics/formation/orbits of each kind
Regular Satellites Irregular Satellites Trojan Satellites
Why is it hard to view Saturn's surface?
Saturn is more remote from warming influence of the sun, so a thick high altitude haze layer (ammonia ice crystals) shrouds the planet-w/o rings it would be much easier to see
Why is there an asteroid belt? How did it form?
The material is stuff that never assembled into a planet; primordial material left over from the early days of the solar system assembly Force of Jupiter prevented the assembly of the matter into a planet
Regular Satellites
These satellites define the outer orbital reaches of a planet's domain in space. Examples include Io, Europa, Ganymede, and Callisto -large and round -tend toward entirely stable, simple, nearly circular orbits -all move through a plane in space that is roughly equal to the planet's equatorial plane -2 formation hypothesis ---they formed out of the same nebula of gas and dust that built the planet, and likely at the same time ---they formed by collision. Our own moon is a great example
Does Jupiter have a magnetic field? How might it be formed?
Yes Not sure how it is generated but likely due to the different motion by different physical states of hydrogen (particularly the metallic state surrounded by the liquid state) Field is the strongest of any body within the solar system
Does Saturn have a magnetic field? If so, what causes it?
Yes, only planet to have perfectly symmetrical magnetic field magnetic poles match the geographic rotational poles weaker than Jupiter, similar to that of Earth
Asteroid
a natural, rocky object in space measuring 100m to several hundred kilometers in diameter
Meteroid
a natural, rocky object in space measuring from a few milimeters to 100m in diameter
The Titus-Bode Law. What does it allow us to predict?
allows us to predict spacing in astronomical units
What is the definition if a POTENTIALLY HAZARDOUS ASTEROID (PHA)?
an asteroid of minimum 150 diameter and comes closer than 0.05 AU to Earth
The TORINO SCALE
an impact potential scale of 0-10 used primarily to convey "level of concern" of an event to the general public -0 No hazard -1 Normal -2-4 meriting attention by astronomers -5-7 threatening -8-10 certain collisions
How does atmospheric friction affect the surface of the meteorite?
asteroid/meteorite has no heat shield to dissipate heat generated by atmospheric friction--leading edges will melt (significant mass is lost--ablation rates are 30-60%) REGMAGYPTS: meteorites with depressions resembling thumbprints that formed by ablation FUSION CRUST: any melting at all will produce a layer of glass objects "burn" as they pass the dense part of the atmosphere--time they reach the ground, they are usually cool to the touch
How does the atmosphere slow a meteoroid's momentum?
atmosphere acts as a brake and effectively reduces the meteoroid's velocity melting phase typically lasts only a few seconds (not enough time to conduct heat into its interior
Where in our Solar System do many asteroids reside?
between Mars and Jupiter, which constitutes the Asteroid Belt
Are the most primitive asteroids closer to Mars or Jupiter?
closer to Jupiter--outer asteroid belt
How does a meteor shower occur? What is the difference between meteor shower and a fireball?
come from specific regions in the sky, and travel together in space in same direction along a common orbit strike Earth's atmosphere are nearly same position along Earth's orbit, and we see a meteor trail against same background of stars FIREBALLS: produced by large chunks of rock and iron that were knocked off asteroid parent bodies by collisions particles in average meteor shower should never reach Earth's surface, but most meteoroids producing fireballs are massive enough to survive atmospheric passage, often explosively disintegrating into several smaller pieces en-route
Where are meteorites on Earth often found and why?
deser regions of Moroco, Oman, and Antarctica--easy to spot them on the ground
What are Kirkwood gaps?
distances between gaps corrssponded to simple fractions of the orbital period of Jupiter--within the gaps, gravitational disruptions are very strong asteroids/meteroids entering these gaps are booted out by Jupiter's gravitational disruption through which meteroids at velocities so great they escape the limits of the Belt gaps are "open doors". where these objects can escape Jupiter's influence and move into the inner solar system (and come to Earth)
How/when do gas giants form?
either formed within the first 10M years of development of a star-planet system or they didn't ever develop idea is that all volatile and liquid elements that would be given off by an early star would gather quickly into frozen blobs in the cold outer regions of the system, there, they would grow and their gravitational attraction would increase rapidly and they'd start pulling greater and greater quantities of volatiles and liquids into themselves the larger masses would start interfering with the orbits of the smaller masses and the combined gravitation/rotational interactions would have the effect of flinging the smaller ones either out to the margins of the planetary systems or in toward the central star
C-type asteroids
high carbon content or 'carbonaceous', 75% of known asteroids; roughly similar composition to the Sun, minus the volatile elements.
S-type asteroids
high silicon or 'silicaceous', 17% of known asteroids.
Describe what we observe happening on Jupiter's surface. What energy is driving the turbulence in the atmosphere? How does this differ from how weather patterns are driven on Earth? What is the Great Red Spot?
interior is responsible for heat flow heat it not the decay of radioactive elements with in the planet that must be occuring, but not nearly at the rate necessary to produce the temp we record theorized that the source of Jupiter's excess energy is the slow compaction of the planet--the atoms of hydrogen and helium move as gravity very slowly pulls them into a more compact configuration, that the motion generates heat
what is a differentiated body?
large asteroids have been heated, by radioactive decay and from the energy released during accretion, enough that their interior starts to melt, as it melts, metal sinks towards the centre and volcanic rock erupt at the surface these differentiated asteroids are broken apart, layers of rocks may be exposed, and we can see the variety of rock types
What are the sources of meteorites that we have found on Earth? How representative of the sources are the samples?
many previously collects on Earth were chips from the surface of the Moon many are also from Mars--these were previously coined as from an "unknown source"
M-type asteroids
metallic, most of the remaining asteroids.
Apollos
most have an orbit that brings them through the orbit of Earth and these are particularly worth watching closely!
Many meteors are destroyed in the atmosphere before they reach Earth's surface-what kinds of meteors (size, speed) are more likely to survive?
most observed fireballs that resulted in surviving meteorites had velocities of around 20-25 km/s many entered the atmosphere at higher speeds and did survive--however they encounter enourmous forces from the pressure of the air resulting their motion pieces of stony meteoroids have a better chance of survival than larger single mass as smaller stones with less mass are more readily slowed in the atmosphere, suffering less heat and ablation--may allow to survive even when main mass has high initial velocity
Are all meteorites from the asteroid belt?
no if an asteroid slams Mars or the Moon, chunks of surface fly off into space, some getting trapped into Earth's gravitational field harder to get meteorites from Venus, as it gets attracted to the Sun's gravitational force
Are meteorites hot when they land? Why or why not?
no, typically cold b/c relatively poor heat conduction of the meteorite's rocky material coupled with the brief heating phase assures survival of the meteorite in pristine condition
What are asteroids and meteorites thought to represent?
objects leftover from the formation of the Solar System last pieces that built the planets -> 4.6 BYA
Why did scientists crash the Galieo spacecraft into the surface of Jupiter? What did we learn?
only craft to orbit Jupiter it was deliberately destroyed by sending it crashing into Jupiter's crushing atmosphere had that not been done there was the possibility that it could contanimate one of its own discoveries--the icy crust of EUROPA scientists now suspect EUROPA has salt water and it may contain microbial
Why did the asteroid belt form between Mars and Jupiter?
originally, they formed throughout the inner solar system, uniformly distributed when planets began to form, it changed the gravitational force drammatically Jupiter's mass allows for it to drammatically alter the motion of small bodies anywhere near it 1st planetoid to grow large before any other planets could accrete where the asteroid belt lies now gravitational discruptions caused by Jupiter's gravity prevented other objects from coalescing into a single planet sized body
If all the meteoroids and asteroids in the main asteroid belt coalsced, would there be an additional Earth-sized planet between Mars and Jupiter?
remaining asteroids, if consolidated, add up to a body significantly less massive than the moon, our Solar System seems to have been robbed of an Earth sized planet beyond Mars
What is the interior structure of Saturn?
small rocky core, a thicker metallic hydrogen inner mantle and the rest is mostly liquid hydrogen with an outermost 1000 km thick layer of atmosphere (mostly hydrogen)
What is a chondrule?
small rounded inclusions in chondrites popular formation theory is that they condensed from a hot cloud of gas and dust, very early in Solar System history, by a "flash-melting" of dust aggregates in the solar nebula
What are the possible sources of micro-meteoroids (aka interplanetary dust)?
solar system is full of dust, concentrated along the ecliptic plane within the planetary orbits--solar system's smallest meteoroids Asteroids in asteroid belt are one source-collisions occure, creating small bodies, continual fragmentation of asteroids creates a micron sized chunks comets are a second source--they trail dusty trails as they rush towards the sun
How does the magnetic field interact with the solar wind and what implications does this have for life
strong magnetic field traps electrically charged particles (from solar wind) and shapes them into a teardrop form of magnetosphere of radiation around the planet--the trapped charged particles are so abundant, that they would damage instruments form any spacecraft flown through the magnetosphere for humans it would be deadly=1 billion chest xrays, 100x the lethal limit
What is causing Saturn to generate heat?
suspected that helium in the liquid hydrogen interior is condensing into droplets and falling inward, the friction in the falling objects and the compaction of them in the core heat the planet
Fireball
the light associated with a large meteoroid or asteroid as it interacts with the atmosphere
Meteor
the visual streak of light associated with passage of a small meteroid through Earth's atmosphere; the heat energy producing the light is the result of friction between the object and molecules of gas in the atmosphere
ATENS
these asteroids have orbits less than 1 AU which means that most of the time they are within the orbit of Earth, though they may cross Earth's orbit when they are farthest from the sun
Amors
these commonly cross the orbit of Mars; get close to Earth's orbit, but don't cross
Irregular satellites
these satellites are of unknown origin -they are almost certainly captured objects and they were captured early in the history of the solar system -many irregulars travel in packs that indicate they were once related objects -typically small -orbit at great distances and often on odd trajectories -orbits are more often than not in retrograde -look to have similar composistions
Why are scientists so excited about studying carbonaceous chondrites?
they contain carbon, and may contain hydrous clay silicates as well as salts taken as a whole, their composition more closely matches that of the sun than other material
Explain why the atmosphere had visible belts and zones. (Same on Jupiter)
zones are higher clouds formed by rising gas and belts are lower clouds formed by sinking gas these clouds are not very distinct on Saturn