Western University Earth Science 1086F Final Exam Study Guide
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Module
Earth Science 1086F (EARTHSCI1086F)
Institution
University Of Western Ontario (UWO
)
This is a full study guide for UWO's Earth Science 1086F Final Exam. Topics include: Meteorites, Asteroids, Planets, Plutoids and TNOs, Comets, and Life in the Universe.
In all chapter words in BOLD are vocabulary words you should know for the exams.
You will NOT be asked to memorize numerical facts (e.g. the density of Jupiter), but you should
be aware of general characteristics (e.g. Jupiter is a gas planet and is less dense than Earth).
The following document outlines the information from each chapter most likely to be tested:
Unit 4 Introduction: From Asteroids to Meteorites
1. Where in our solar systems do many asteroids reside?
a. The Asteroid Belt (b/w Mars and Jupiter)
2. Why is there an asteroid belt? How did it form?
a. Material left over from the formation of planets
b. Instead of accretion, Jupiter prevented it from collecting
3. Are all meteorites from the asteroid belt?
a. Not all of them, some from Mars, Moon (chunks from impacts)
4. Definitions: Asteroid, Meteoroid, Meteor, Fireball, Meteorite
a. Asteroid: rocky body in space (100m to 100km)
b. Meteoroid: rocky body in space (few mm to 100m)
c. Fireball: light from large asteroid/meteoroid in the atmosphere
d. Meteor: light from small meteoroid in the atmosphere
e. Meteorite: fragment that LANDS on the Earth
5. You do not need to know how to calculate estimates for planetary orbits using the Titius
Bode Law, but please be aware that such a law exists – what does it allow us to predict?
a. Allows us to predict positions of the planets in AU
6. It’s important to learn whatever we can about asteroids because
a. They represent very primitive material left over from formation of the 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 humans)
Chapter 12: Asteroids
1. Where are most asteroids found in the solar system?
a. Asteroid Belt
2. What are asteroids and meteorites thought to represent? (e.g. age and material)
a. Represent primitive material from the formation of Solar System, 4.5 billion yrs
3. Why did the asteroid belt form between Mars and Jupiter?
a. Force from Jupiter prevented the material/planetesimals from accreting into planet
b. Originally distributed throughout system, but planets pushed these out to Jupiter,
strong gravity
4. What are the Kirkwood gaps?
a. Gaps in the Asteroid Belt where no asteroids exist (2.5, 2.8, 3.2 AU)
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, b. Regions where gravitational disturbances are strong (gravity from the Sun and
Jupiter), any asteroid that enters the gap will be pulled either toward the Sun or
toward Jupiter, leaving the gap clean
5. If all the meteoroids and asteroids in the main asteroid belt coalesced, would there be an
additional Earth-sized planet between Mars and Jupiter?
a. May have originally been able to, but much material is lost now
b. Remaining would only accrete into a body less massive than the Moon
6. What is the difference between C, S, and M type asteroids?
a. C-type: high carbon, “carbonaceous”, 75%
b. S-type: high silicon, “silicaceous”, 17%
c. M-type: metallic, remaining asteroids
7. Why are some asteroids metallic while others are not?
a. Depends on where they are formed (temp)
8. Are the most primitive asteroids closer to Mars or Jupiter?
a. The most primitive asteroids are closer to Jupiter
b. The most altered/differentiated are closer to Mars
9. How can asteroids be classified using albedo and spectral analyses? There is no need to
memorize the names of specific types of asteroids.
a. Albedo: amount of light reflected from object
i. Those with more metal reflect more light, those with more carbon don’t
b. Spectral Analysis: break down the reflected light to see which minerals are
reflecting it
10. Why are the most plentiful asteroid types (carbonaceous chondrites) the least common
meteorites found on Earth?
a. C-type asteroids are more common in the middle to outer belt
b. Difficult to remove them from the outer belt (close to Jupiter)
11. What is a differentiated body?
a. Asteroids can be heated (radioactive decay or accretion forces), and melt
b. Metal/heavy elements sink in to core, lighter elements stay at surface, creates
layers of different rock
12. You do not need to memorize the various material that make up Vesta.
a. One of the brightest in the sky, changing reflection
13. Give an example of the kinds of features the spacecraft Dawn has observed on large
asteroids.
a. Impact history, crustal mineralogy, morphology
b. mountain
14. What is an asteroid family? When two asteroids of unequal size collide, will the
fragments come from the larger body or the smaller one?
a. Breakup of an asteroid into smaller fragments, with similar orbital characteristics
b. Fragments usually come from larger, smaller usually melted
15. Do near Earth objects have circular or elliptical orbits?
a. Near Earth Asteroids, not in Main Belt
b. Elliptical orbits, based on their distances
16. Define Atens, Apollos and Amors (near Earth asteroids)
a. Atens: less than 1 AU from the Sun, within Earth’s orbit and only cross it when
furthest from Sun
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, b. Apollos: 1 AU from the Sun (same as Earth), most cross Earth’s orbit (WATCH)
c. Amors: more than 1 AU, cross Mars’ orbit but never cross Earth’s (get close)
17. What size of an impactor could cause global effects on Earth?
a. Larger than 1 km in diameter
18. What are Trojan asteroids?
a. Asteroids located 60 degrees above and behind Jupiter’s orbit (Langrangian
points)
i. Gravity from Sun and Jupiter is combined
19. What is the definition of a PHA? (Potentially Hazardous Asteroid)
a. Asteroids of at least 150m diameter and closer than 0.05 AU from Earth
20. You do not need to memorize the Torino Scale, but you should have an idea of what it
means as you move to higher and higher numbers.
a. Scale of 0-10, relative risk/hazard of asteroid or comet impact
b. 0 is no hazard of collision, 10 is certain collision causing global damage
Chapter 13 - Meteorites
1. What are the sources of meteorites that we have found on Earth? How representative of
the sources are the samples?
a. Moon, Mars
b. Chips from the surface
2. What is the difference between a find and a fall?
a. Find: stumble across it, no info on when it fell
b. Fall: fall was observed and object was recovered partially/fully
3. What is the difference between irons, stony-irons and stones? Which is the most
commonly found on Earth?
a. Iron: iron and nickel
b. Stony-Irons: mix of metal alloys and silicate
i. Most common on Earth
c. Stones: silicate/oxides
4. Within the Stones category, what is the difference between chondrites and achondrites
a. Chondrites: aggregates of sediment, never greatly altered since formation (95%)
b. Achondrites: igneous, at least partially melted since formation (4%)
5. What is a chondrule? How might they have formed?
a. Rounded inclusions in chondrites
b. Condensed from hot cloud of gas/dust by ‘flash melting’ in solar nebula
6. Why are scientists so excited about studying carbonaceous chondrites?
a. Their composition closely matches the Sun than anything else
7. What is the difference between an achondrite and a primitive achondrite?
a. Achondrites are completely melted into igneous rock
b. Primitive achondrites still contain residual rock that didn’t melt
8. What are the possible sources of micro-meteoroids (a.k.a. interplanetary dust)
a. Asteroids (collisions) and comets (dust tail)
9. How does a meteor shower occur? What is the difference between a meteor shower and a
fireball?
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