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Where in our solar systems do many asteroids reside?
Most asteroids reside in the gap between Jupiter and Mars - also named the Asteroid belt or main asteroid belt.
Why is there an asteroid belt? How did it form?
Orbital resonances with Jupiter prevented planetesimals between Jupiter and Mars from
forming a planet. Therefore, all the planetesimals that could form a planet are trapped in
this gap due to Jupiter's strong gravity
Are all meteorites from the asteroid belt?
Not all meteorites are from the asteroid belt. Some such as atens, amors, and Apollo asteroids are really close to the Earth and Mars, which is out of the asteroid belt.
Definitions: Asteroid, meteoroid, meteor, fireball, meteorite
Asteroid: A natural rocky object in space measuring over 100 m in diameter
Meteoroid: A natural rocky object in space measuring less than 100 m in diameter
Meteor: A small streak of light associated with the entering of a small meteoroid entering the sky - the light is a result of the burning caused by the friction between the object and atmosphere
Fireball: A large streak of life associated with the entering of a large asteroid or meteoroid entering the atmosphere.
Meteorite: An object of any size of either an asteroid or meteoroid that lands on the earth's surface.
What does the Titius Bode Law allow us to predict?
It allowed human to predict the AU between planets by adding and multiplying based on
simple decimal numbers.
It's important to learn whatever we can about asteroids because...
a. They represent the very primitive material left over from the formation of solar system.
b. Much water and organic material came to Earth from them
c. Sooner or later a large asteroid impact is likely to put an end to many terrestrial species including human
Where are most asteroids found in the solar system?
Most are found in the area known as the Main Asteroid Belt between Mars and Jupiter.
What are asteroids and meteorites thought to represent?
Ancient Greeks & Romans used to think that meteorites are "betyls" - chunks of the god's house. Meteorites are also found entombed to Egyptian Pharaohs. Overall, they are valued really preciously by ancient Greeks, Romans, & Egyptians.
Why did the asteroid belt form between Mars & Jupiter?
Jupiter's huge gravitational pull avoided the planetesimals between Jupiter and Mars to form, resulting in asteroids that could have formed a planet. This is why there is such a big gap between Mars and Jupiter as there really should be another planet.
What are the Kirkwood gaps, and what causes them?
The Kirkwood gaps are spaces in the asteroid belt where no asteroids exist. It is caused
by the extremely strong gravitation of Jupiter in that area which any asteroids entering would get swung out and fly towards the inner solar system.
If all the meteoroids and asteroids in the main asteroid belt coalesced, would there be an additional Earth-sized planet between Mars and Jupiter
No there wouldn't. Because the sum of everything in the asteroid belt is just a little smaller than the moon. Therefore, if possible, the planet would be smaller than the moon.
What is the difference between C, S and M type asteroids?
C type - Carbon: accounts for 75 percent of the asteroids, high in carbon
S type- Silicate/Silicon: accounts for 17% of asteroids, high in silicon
M-type - Metallic: accounts for the remaining, high in metal/metallic, very reflective/high-
albedo
E type - Enstatite: Asteroids with the highest albedo(40%)
Why are some asteroids metallic while others are not?
Really large asteroids undergo differentiation and can be left with a nickle-iron core and a metallic body.
Are the most primitive asteroids closer to Mars or Jupiter?
Asteroids with low albedo are believed to be composed of the most primitive material. Near Mars/Sun most metallic/high-albedo asteroids are found, while closer to the edge of the belt & Jupiter where most carbon/low-albedo asteroids are found.
Therefore, the most primitive asteroids are found closer to Jupiter.
How can asteroids be classified using albedo and spectral analysis?
Asteroids can be classified by using albedos because carbon high asteroids reflect least
light and metallic asteroids reflect the most light. Similar asteroids with similar light reflection can be classified similarly. Spectrometers are also used to break down the reflected light into a spectrum which can tell us which minerals reflect light.
Why are the most plentiful asteroid types (carbonaceous chondrites) the least common meteorites found on Earth?
Because carbonaceuous chondrites are composed of several minerals at a time - meaning they came from one or more planet bodies.
What is a differentiated body?
A differentiated body is a body that is heated - which causes the melting of interior where metal can sink in.
Give an example of the kinds of features the spacecraft Dawn has observed on large asteroids
4 Vesta is the largest asteroid and one of the brightest in the sky to the naked eye.
Dawn discovered that 4 Vesta has a meta-rich core that is half its diameter. It also found
that the biggest mountain on 4 Vesta is bigger than the one on Earth.
What is an asteroid family? When two asteroids of unequal size collide, will the fragments come from the larger body or the smaller one?
When two asteroids collide, the larger asteroid will experience greater stress meaning the collision fragments will usually come from the larger one.
Family=The breakup of asteroid into a collection of fragments.
Do near Earth objects have circular or elliptical orbits?
All of them have highly elliptical orbits.
Define Atens, Apollos, and Amors
Atens: Asteroids with orbits less than 1 AU - meaning they are within the orbits of Earth.
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Apollos: Asteroids that cross the Earth's orbit
Amors: Asteroids that cross the orbit of Mars and get close to earth's orbit.
What is the definition of a PHA?
Potentially Hazardous Asteroids (PHAs)
- minimum 150 m diameter
- 0.05 AU to Earth
What are Trojan asteroids?
They are asteroids that are about 60 degrees ahead and behind Jupiter in Jupiter's orbit.
What size of an impactor could cause global effects on Earth?
Minimum 1km.
- Apollo asteroids
What is the Torino scale?
a system used to rate the hazard level of an object moving toward Earth.
10 means a collision is certain - capable of causing a global effect
0 means a collision's likelihood is zero
What are the sources of meteorites that we have found on Earth? How representative of
the sources are the samples?
Most of the meteorites found on earth are actually chips from the surface of the Moon and Mars. The sources are representative because they were examined according to the materials collected on the Moon and Mars.
What is the difference between a find and a fall?
Find meteorites are found unintentionally with no information of how it got here
Fall meteorites are witnessed through entering the atmosphere and then was recovered
by someone.
What is the difference between irons, stony-irons, and stones? Which is the most commonly found on earth?
Stone: non metallic, Make up 93% of all meteorites - divided into chondrites & achondrites.
Stony iron: 50/50 mix of metallic and non-metallic materials, make up 1% of meteorites
Iron: metallic materials (iron + nickle), make up 6% of meteorites.
Within the Stones category, what is the difference between chondrites and achondrites?
Chondrites: a meteorite that has never been altered or melted
Achondrites: An igneous rock that has been at least partially melted or recrystallized.
What is a chondrule? How might they have formed?
Chondrules are small, rounded inclusions (holes) in chondrite
They are condensed from a hot cloud of gas and dust. very early in the Solar System.
Why are scientists so excited about studying carbonaceous chondrites?
Carbonaceous chondrites are fascinating because they may contain carbon - which may have diamonds, graphite, organic molecules which are the building blocks of life.
What is the difference between an achondrite and a primitive achondrite?
Achondrite: An igneous rock which is partially or fully melted.
Primitive achondrite: A residual rock (rock left behind that didn't melt)
What are the possible sources of micro-meteoroids (interplanetary dust)?
Interplanetary dust are Solar System's smallest meteoroids which orbit the Sun. The sun's gravity constantly push them out of the solar system so there needs to be sources
which constantly replace the ones that are being lost.
1. Asteroids: Collision in the asteroid belt break into small particles which turn into interplanetary dust.
2. Comets: Dusty trails from comets left to form the interplanetary dust.
How does a meteor shower occur? What is the difference between a meteor shower and a fireball
Meteor shower comes from specific region and strikes the earth's atmosphere at the same position along Earth's orbit.
Fireball: Large chunks of asteroid knocked off by collision which light up due to the burning friction between its body and the atmosphere.
Difference: Meteor show does not reach earth's surface but fireball is powerful enough to break through and land on earth.
How is the light of a fireball formed? Why do the colours change?
The light of the fireball is the burning of the body itself caused by ablation and the lighting of atmosphere surrounding it.
The colour is 1. Vaporizing of the material & 2. Luminous air surrounding the fireball.
Colour changes because elements give off different colors when vaporized - Bright white to Red.
Are meteorites hot when they land? Why or why not?
Yes, atmosphere heats up meteorites to extremely temperature that ablation occurs - losing mass.
How does the atmosphere slow a meteoroid's momentum?
Atmosphere slows down its momentum by creating drag - slowing down its velocity.
Explain how a meteoroid's mass and velocity affects its momentum and kinetic energy?
The greater the mass and velocity, the greater the momentum and kinetic energy.
Many meteors are destroyed in the atmosphere before they reach the Earth's surface - what kinds of meteors (size, speed are more likely to survive)?
Larger/high velocity/high momentum meteoroids don't survive. If the meteoroids are broken into smaller pieces they have a higher chance of avoiding ablation and heating.
How does atmospheric friction affect the surface of the meteorite?
- Their edges will melt
- Surface are marked with thumbprint marks.
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Where are meteorites on Earth often found and why?
Desert / Arctic - where it's open ground and easy to spot.
- Antarctica is the best place: it's coldness preserve the meteorite, and its open ground.
What techniques do we use to analyze a meteorite? What can we learn from the test?
Petrographic microscope: Identify mineral composition of meteorite.
Electron micropobe: Uses tiny beam of electrons to identify what elements are present.
Mass spectrometer: Measures radioactive isotopes to see how old sample is.
Definitions of a gas giant planet (Jovian Planet)
A large, low-density planet composed primarily of hydrogen, helium, methane, and ammonia in gas or liquid state.
What are the 4 gas giants in our solar system?
Jupiter, Saturn, Uranus, Neptune
What are the common features shared by gas planets?
- low density
- very hot core
- Mainly made of hydrogen and helium, my hydrogen.
- All have satellites/rings
- All rotate rapidly resulting in strong atmospheric wind.
How/when do the gas giants form?
Either formed in the first 10 million years of solar system or did not develop.
Volatile and liquid elements - grew via gravitational attraction and increased by pulling greater and greater quantities of volatile liquids to them.
What did we learn by watching the Shoemaker-Levy 9 comet impacting Jupiter?
1. It better allowed us to study and represent Jupiter's atmosphere.
2. It reminded us that planets are being hit by large objects all the time.
How do we know that Jupiter is big?
We know that Jupiter is big because it looks big. Io's shadow displays visible contrast to Jupiter's size.
How do we know that it is hot? Why does it have a high heat flow (what is the internal heat engine)
We know that it's hot because it emits 1.7 x energy that it receives from sun - meaning it
has a hot core that generates energy.
It has strong wind circulation.
Describe what we observe happening on Jupiter's surface?
There are very strong winds. the Great Red Spot (GRS) is a cloud of rotating storm caused by heat rising upwards.
Why did scientists crash the Galileo spacecraft into the surface of Jupiter? What did we learn during this descent?
Galileo was crashed to the surface of Jupiter because it could contaminate the icy crust of Europa that main contain microbial life.
We learned the crushing atmosphere of Jupiter as how hard it was for Galileo to crash in.
Jupiter is primarily composed of hydrogen in various states, describe the structure of the
planet. Does the liquid hydrogen ocean have a surface?
It goes from gas to liquid to metallic to a rocky/metallic/hydrogen core. There is a liquid hydrogen ocean with a gas layer on top of it.
Does Jupiter have a magnetic field? How might it formed?
Yes it has a core 14 x than the earth's. Caused by the different physical states of hydrogen surrounding the core.
How does the magnetic field interact with the solar wind and what implications does this
have for life? (humans or aliens)?
Jupiter's magnetic field traps electrically charged particles from solar wind and shapes them into a deadly radiation around the planet.
- Humans would die instantly, equivalent to billion chest X-rays.
Explain how the dark belts and bright zones result form in Jupiter's atmosphere
Dark belts=regions of descending gas of the clouds of Jupiter
Light zones=regions of rising gas result from the rotation of the planet.
What are the 3 classification of satellites (for Jupiter's satellites and elsewhere)?
Regular satellite:
- Define the outer orbital reach of the planet
- Large and round
- Circular orbit
- Formed by the same gas which built the planet
- Io, Europa, Ganymede, Callisto
Irregular Satellites:
- Satellites of unknown origin
- usually captured
- small
Trojan Satellites:
- Satellites that orbit the sun, but is also gravitational bound to its planet at the same time.
- Ahead and behind Jupiter
What are the 3 principles in comparative paleontology?
1. A body's composition depends on the temperature of the material from which it formed
2. Cratering can tell us the age of the surface
3. Internal heat has powerful influence over the geology of large satellites.
Name the 4 Galilean Moons of Jupiter
Callisto: Ice and rock, undifferentiated interior, weak magnetic field, no atmosphere
Ganymede: Silicate rock and ice, differentiated interior with molten iron core, generates its magnetic field, has an oxygen-rich atmosphere.
Europa: rock and metal, metallic core, no magnetic field, icy body with ocean (chance of
microbial life), has temporary oxygen/hydrogen atmosphere
Io: iron rich core, filled with volcanoes, closest and fastest that orbits Jupiter, atmosphere of oxygen + sulfur.
Flights to jupiter: Pioneer 10, Pioneer 11, Voyager 1 and Voyager 2, Galileo, New Horizons, Juno
Pioneer 10: Pioneer 10 has now left the Solar System. Scientists mounted a plaque on the
spacecraft that displayed diagrams capable of being translated by any scientifically
educated civilization that might encounter the spacecraft in the future (ever see the movie:
Star Trek V: The Final Frontier? A fictional Pioneer 10 was used for target practice –
and easily destroyed – by a Klingon Bird of Prey).
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Galileo: after 14 years of flight time and 8 years collecting data around Jupiter, Galileo was deliberately destroyed by sending it crashing (at 50 km/s) into Jupiter’s crushing atmosphere.Galileo had a lot of ‘firsts’ to its credit: for example, it was the first probe to fly past an asteroid (asteroid 951 Gaspra on October 29, 1991 and asteroid 243 Ida on August 28,
1993). Galileo changed the way we think of the Solar System.
Jupiter actually emits about 1.7 times as much energy as it receives from the Sun).
Why do Europa and Io have few craters (two different reasons)?
Europa: The surface resurfaces periodically - liquid water from underlying ocean rises through cracks in ice to flood over surface and reshapes the surface.
Io: 150 active volcanoes blast gas/lava out to bury new craters formed on surface.
Which of these satellites might have some possibility of supporting life? Why?
Europa; because it has liquid water/ice.
Why is it hard to view Saturn's surface?
Because it is covered by a thick high-altitude haze which surrounds the planet.
How did Cassini Huygens spacecraft get enough energy to reach Saturn's orbit?
It used solar power to move; consumes energy used as little fuel as possible.
Why is Saturn less dense than Jupiter?
They have the same composition, but has more hydrogen (the lightest element)
What is the interior structure of Saturn?
rocky core, thick mantle of liquid metallic hydrogen and helium, rest is liquid hydrogen with a hydrogen atmosphere.
What is causing Saturn to generate heat?
The friction and compaction of falling Helium liquid hydrogen causes core to heat the planet - it emits 1.8 times the energy it receives from the sun.
Saturn and Jupiter are similar in that there is no clear division between the atmosphere and the surface. Be sure you know why this is happening.
Because they both don't have surfaces, it goes straight from gas atmosphere to liquid hydrogen.
What are the 2 main components of Saturn's atmosphere?
91% hydrogen & 6% helium.
Explain why the atmosphere has visible belts & zones (same as Jupiter)
Belts=lower clouds by descending gas
Zones=higher clouds by rising gas
Belt zone=circulation of gas.
Does Saturn have a magnetic field? If so, what causes it/
Saturn has perfectly symmetrical magnetic field - caused by the interaction between core and metallic hydrogen inner mantle.
Why are there gaps in the rings of Saturn?
Caused by the gravitation of Mimas - Saturn's moon. Rings particles are effected by Mimas gravitation over time.
What are the rings composed of? Do other gas giants have rings? Compare differences in formation of rings among the gas planets
Saturn's rings are made of water particles of ice; some dirt. Saturn's rings are extremely
bright, wheres uranus and neptunes' rings are darker.
Why are the rings orbiting Saturn's equator rather than spread in a haze about the whole planet?
Due to Saturn's gravitational pull, its gravity is centered at the equator and compressed at the pole - therefore there's a greater gravitational pull near the equatorial zone.
Do we know what causes the appearance of "spokes" on the B ring?
Spokes are dark radial features that move in patterns on the B ring.
It might be a seasonal phenomenon as it disppears and reappears again, but we don't know the reason.
Do collisions of particles in the rings make particles larger or smaller? Explain
Collisions of particles in the rings make bigger particles smaller and smaller particles bigger.
Outline the evidence that suggests the material in Saturn's ring is young
- Uniformity of material in rings
- Ice blocks reflecting are fresh looking (no dust)
- Can't be that old
What are the arguments that suggests the rings might be old?
Rings are not always uniform all the way around. Regions that are young cannot represent its age.
What is a possible source of the water/ice in its rings?
The rings were once a water-ice, rocky-core satellite of Saturn which was ripped apart and formed the rings.
Titan has an atmosphere and continents making it like Earth. Let's compare their properties:
1. What is the composition of Titan's atmosphere?
- 98.4% nitrogen, just like Earth
2. Is the surface hot or cold?
- Cold
3. What is special about the volcanic activity on Titan?
- The volcanoes are cryovolcanoes, which erupts cold water/ice instead of lava.
4. What is the source of methane in the atmosphere on Titan vs Earth?
Methane in the atmosphere of Titan are from volcanoes. Methane on earth are from biological life.
5.What are Titan's dunes composed of?
- Methane crystals
5. Does Titan have the ingredients required for life?
- Not now, even it may contain organic molecules, there is no carbon dioxide and the surface is too cold. when the Sun turns into a red giant which heats up its surface it may.
Which of Saturn's satellites look like the Death Star from the Star Wars movies?
Mimas
Iapetus - also shows an enormous impact crater (just at the day/night line) but
it is clearly very old because many younger craters appear inside. The most striking
feature of Iapetus, however, is not the crater but the equatorial ridge that goes all the way
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around the visible part of the satellite.
What process result in Enceladus having liquid water at surface?
Fictional kneading created heat to make liquid water.
What is shepherd satellite and how do they stabilize rings?
Shepherd satellites are moons that surround and stabilize a saturn ring. Gravitation drags particles to its original place on rings.
Why are Uranus and Neptune considered "ice giants"
gas=hydrogen/helium ice=water/ammonia/methane
Uranus/Neptune have more ammonia/methane in their atmosphere and planet.
Do these planets have rings? What might be the source of material for the rings?
Both have dark rings. May be impacts from small satellites or comets.
Contrasts the internal heat of these two planets. Why might Uranus be cold? Where does Neptune's heat originate?
Uranus generates just as much heat as it receives from the sun - might be due to the event the planet over.
Neptune generates 2.6 x the heat it receives from the sun, due to radioactive decay in rock and friction of materials.
Neither Uranus nor Neptune can be seen from Earth with the naked eye - Explain what theories were used to predict their locations
Titus-Bode Law
What is unique about Uranus's rotation, what caused this and how does it affect its seasons?
Each pole of Uranus receives 42 years of sunlight and 42 years of darkness.
What is the internal structure of Uranus and Neptune?
Both have rocky cores, and then liquid hydrogen helium.
Why do uranus and Neptune have less hydrogen and helium than Saturn and Jupiter?
Their atmosphere's escape velocities are low, resulting in easy escape of hydrogen and helium.
Do these planets have magnetic fields? What creates them?
Uranus: similar to Saturn, magnetic generated from the south pole, same magnetic field as the earth.
Neptune: half as much as earth's
What's in the atmosphere that makes the planets appear blue-green
Methane
Although Uranus and Neptune have similar atmospheres, Neptune is a bit hazy, why?
Between the stratosphere and troposphere, there's a concentration of organic molecules which make the atmosphere hazy.
What is the difference between conduction, convection, and radiation?
Conduction: Heat energy transmitted through physical contact/collision
Convection: Heat transfer by motion of fluid and gas
Radiation: Energy transmitted in forms of rays, electromagnetic waves or particles.
Some features of the 5 satellites of Uranus
- All dark in colour (dark lava)
- Convection drives active tectonics
- All have water
Why might Triton crash into Neptune?
Triton travels in opposite direction to Neptune. The tidal interaction between the two removes its energy meaning its orbit will eventually crash into Neptune's orbit.
Why does Triton have an atmosphere
The high density and immense cold gives the planet enough escape velocity to sustain an atmosphere
Triton is very cold - what element is liquid on the planet and how does this affect surface
features?
The liquid nitrogen acts like water which forms the subsurface layer on Triton.
What is the probable source of heat that drives activity on Triton?
The opposite orbit relative to Neptune generates internal heat which gives it energy.
Definition of a plutoid
1. Orbits the sun at a distance further than Neptune
2. Has not cleared its neighborhood around its path
3. Gravity big enough to make it a sphere
What is the name of the plutoid that is bigger than Pluto?
Eris
Comets for plutoids
1. Made of frozen gases / rock fragments
2. Has elliptical orbit travelling through the solar system
3. Anchored within Kuiper Belt and Oort Cloud
What are the names of the 4 dwarf planets describe as plutoids?
Pluto, Eris, Makemake, Haumea
Why was pluto demoted from planet status?
Pluto does not clear its neighborhood.
What is a trans-Neptunian object?
Any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune.
Where are the Kuiper Belt and Oort Cloud located?
Kuiper Belt: Past pluto
Oort Cloud: further than Kuiper Belt near the edge of the S.S
What is the name of the spacecraft that recently visited Pluto?
New Horizons
What is Planet X?
The mysterious planet 6 degrees away from pluto.
Is Pluto always further from the Sun than Neptune? Why or why not?
Not always, every 248 years, Pluto swings inside orbit of Neptune and stay there for 20 years - which is then closer to the sun.
What 4 kinds of ice are found on Pluto's surface?
Methane, nitrogen, carbon monoxide, carbon dioxide
Why is Pluto's surface not heavily cratered?
Because it is cold enough that everything freezes over. In Tombaugh Reigo smooth plain called Sputnik Planum, the ice are very young and are active.
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Does Pluto have an atmosphere?
It has a thin atmosphere. It is so cold that the vaporization of nitrogen, carbon monoxide, and methane to form a thin atmosphere.
What is Pluto's interior?
frozen nitrogen, water ice, and silicate rock.
Is Charon a satellite of Pluto?
Charon is Pluto's largest satellite - it orbits pluto in near circular orbit, their gravitational balance point is between them, meaning pluto has a really weak gravitational pull - and can argue that Charon is not a satellite.
Why is there almost no methane on Charon, while Pluto has lots?
Charon is too small to hold off methane therefore gas escapes. Pluto catches a lot of it leaking off Charon.
What is the main kind of ice on Charon?
Water ice
Does Pluto have satellites?
4 - Nix, hydra, Kerberos, Styx
What do we know about Eris
Largest Plutoid - little bigger than Pluto.
Composed of methane ice.
What is the Scattered Disk?
Disked shaped region beyond the Kuiper belt with objects that have random orbits out at the edge of solar system - starts at Kuiper Belt and extends out.
What are comets?
Small, icy masses that orbit the sun that are greater than 100 m in diameter
Where do comets come from?
Kuiper Belt and Oort Cloud
What are comets made of?
Basic building blocks of life, carbon rich elements, amino acids
What do comets represent?
Evidence that comets brought water to earth, making life possible.
Why life cannot survive on comets even though there are amino acids?
It's flying through space resulted in extremely low temperatures, high vacuum, radiation,
UV light, etc which all do not enable life to survive.
What are the 4 parts of a comet?
Nucleus: main body of the comet - dust, frozen gas
Coma: When the nucleus vaporizes and turns the surface into vapor releasing a small atmosphere surrounding the nucleus.
Tail
Ion tail: made of charged particles; blown away by solar wind
Dust tail: follows comet's orbit - made up of dust particles that reflect light.
How are comets related to meteor showers?
You can see meteor showers from earth because it passes through stream of dust, like the dust tails on a comet.
Which direction does each of the tails point to?
Away from the sun
What is the difference between long period and short period comets?
Long period comets: Take more than 200 years to orbit the sun - from the Oort Cloud
Short period comets: Take less than 200 years to orbit the sun - from the Kuiper belt. & Scattered Disk
Why are the lives of short-period comet limited
Because its nuclei does not have enough energy to sustain for too long.
What is the typical lifespan of a short period comet?
0.5 million years
What is the Kuiper Belt? How did it form?
Icy objects in a belt surrounding the Sun past Pluto. The materials are the remnants of the beginning of the solar system.
For what 2 reasons is the Kuiper Belt significant for study of the solar system?
1. The objects in the Kuiper Belt are from the primitive remnants of the early solar system
2. It is the source for short-period comets
How do TNOs become comets? How can we tell which process created it?
1. Planets' gravitation kicks out an icy body from its orbit and fly towards the solar system.
2. Two icy bodies collide and fragments come flying to the inner solar system.
We can tell by examine its nucleus, if its undamaged and nice, then it's from gravitation. If it is angular, then it has suffered a damage.
What is the Oort Cloud? How did it form?
Icy bodies that drifted away from the solar system since the beginning. Place for long-
period comets.
Based on their orbits, how do we know that long-period comets come from the Oort Cloud?
Their orbits are 50% retrograde and 50% prograde, with a random distribution like that it
has to come from the Oort Cloud.
What is Comet Halley coated with? What is the surface of Comet Borrelly?
Comet Halley is coated with organic material
Comet Borrelly is cotted with a dark charocal like substance.
Have we collected a material from a comet yet?
Collected organic compounds from Wild 2
Can comets carry viruses?
No they can't
Why has Halley's comet become one of the most well-known comets by humans?
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Because it repeats itself every 76 years. Human used to thought that comets travel in straight lines.
Can you see comets with the naked eye?
Yes but it has to be closed. It also needs to undergo ablation which would result in lighting.
What are the 6 possible places we hope to find evidence of life in our solar system?
Europa, Ganymede, Enceladus, Titan, Clouds of Venus, Mars.
What do we think life requires to develop?
Water + not too hot/cold
Why does living matter need energy?
It utilizes energy from environment to survive and create offspring.
What is the simplest life-form we are aware of?
Bacteria
Is a virus a life form? Why or why not?
No it's not, they have no cells - require a host
What is a cell? What are nucleic acids composed of?
Cells are discrete units that composed for the essential characteristics of life.
Nucleic acids are compound composed of sugar, phosphate group, nitrogen.
What is the role of DNA, RNA?
DNA: a form of nucleic acid that carries genetic information of all organisms. It's primary
role is to contribute information to production of chemical reaction in cells.
RNA: carries out coded instructions given by DNA.
Why is life on earth carbon based instead of silicon based?
Carbon atoms bond to form complex, stable chains to utilize energy.
Describe how the process of natural selection results in evolution of species?
The species with a distinct advantage will survive and be passed on to offsprings; which
enhances the entire species. Merciless at individual, but gives species best chance of survival.
What is our definition of life?
1. Cellular organisms
2. Carbon/Water based
Contain genetic information
4. Undergoes metabolism and adapts to environment
5. Respond to stimuli and undergoes natural selection/evolution.
What was the Miller-Urey experiment? What did he create and what was the significance?
Demonstrated how inorganic elements could combine with necessary requirements to form organic chemicals. Used lightning to represent the past atmosphere and amino acids appeared.
What evidence of life has been found in meteorites?
Amino acids + organic compounds, same as the one produced in the Miller Urey experiment.
What is primordial soup?
a solution rich in organic compounds in the primitive oceans of the earth, from which life
is hypothesized to have originated.
How/where might amino acids link together to form larger molecules
Compounds dissolved and linked together to form molecules in earth's ocean
How old is the oldest fossil?
3.5 billion years old
Stromatolites, some of the earliest complex organisms, produced oxygen which was toxic to them - how did they survive? Is this process still happening today?
The ocean back then was full of iron, once the oxygen was produced, it was instantly dissolved. It would not happen today because the ocean changed.
What is the difference between a prokaryote and eukaryote
Prokaryote: single-celled organisms lacking complex internal structures
Eukaryote: Multi-celled organisms with nucleus, and more complex features; live by respiration through oxygen for energy.
Why do we need ozone?
Blocks ultraviolet radiation from reaching the surface which breaks down Amino Acids. At least 2% oxygen is needed in the atmosphere to produce ozone.
What is the Cambrian explosion and when did it happen?
An explosion of a more complexity of life caused by the change in climate.
When looking for life elsewhere in the solar system or universe why do we look for liquid
water?
It is important because water transport nutrients and wastes within organism.
What conditions prevent life on the planet in the inner solar system (terrestrial planets) vs the outer solar system (gas giants)?
Too hot or too cold; temperature
What are the arguments against life on the satellites Europa, Ganymede, and Titan?
Europa (best chance): has liquid water below its icy crust. But cannot sustain for billions
of years for life to develop.
Why were scientists excited to see Methane on Mars?
Because Methane could be a sign of active biological activity
Was/is there liquid water on Mars?
Liquid water could have existed on Mars longer than it took life to evolve on earth.
What is the habitable zone?
region around a star where liquid water could be present on a planet's surface
When looking for planets outside of our solar system that might have life, what characteristics do scientists look for?
1. Terrestrial
2. exist within the habitable zone
3. has liquid water
3. right temperature
Why is it unlikely to find planets with life orbiting in...
Binary stars - most planetary orbit is unstable
Large stars - too hot
Small stars - too cold
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Astronomers have been searching for other planets that might have the right characteristics of life - have they found many potential candidates
Kepler-186f, Kepler-454b, Tau Ceti e
What are the drawbacks of communication with other planetary systems by radio waves
Radio waves travel at the speed of light. To get a message from a planet 10 light years away, it will take us 20 years suppose they respond the second they received it.
What are the 3 common characteristics of a mass extinction on earth?
Short period of extreme catstrophism
2. Global context
3. Disturbance in both marine and terrestrial environments.
By the end of this chapter you should have a good idea of the physical properties of planets that might support life, but also pay attention to the time factor – how long did it take for life to evolve on Earth? What about intelligent life? Given that planets can move out of the goldilocks zone or that all life can be wiped out by an extinction event, finding intelligent life elsewhere will be difficult.
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