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Western University Earth Science 1086F Midterm Study Guide
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This is a full study guide for UWO's Earth Science 1086F Midterm Exam. Topics include: Big Bang Theory, Nebular Hypothesis, Solar System, and Planets.
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1086F Study Guide:In all chapters, 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 1 Introduction: Basic Concepts
1. What observations led to the acceptance of the Big Bang theory?
a. Recession of Stars and Galaxies (Doppler shift)
b. Cosmic microwave background radiation
c. Abundance of light elements
2. What are the steps of the scientific method?
3. How to define and measure time and space
Chapter 1: Big Bang Theory
1. Define hypothesis, theory, and law. What are the differences between them?
2. What is a singularity
3. What is the Big Bang theory? What does it describe?
4. What are the three main lines of observation that support the Big Bang theory?
a. Describe the Doppler shift
b. Explain cosmic microwave background
c. Abundance of light elements
5. What are the possible shapes of the universe?
a. Spherical, Saddle, Flat
6. What makes up the most matter in the universe, dark matter or stars (conventional
matter)?
a. Dark matter = 27%, Conventional = 5%
7. What is the difference between dark matter and dark energy?
a. Dark Matter = gravitational attraction to conventional matter
b. Dark Energy = opposite of gravity, counteracts the expansion of universe
8. How can we know the age of the universe? (3 ways)
a. Radioactivity – gas compositions of stars/processes/time for processes (11.5-17.5
billion years)
b. Hubble’s Expansion Constant – can be used to find age of distant stars (time
factor), date White Dwarfs (if 13 billion years old, cosmos from Big Bang need 1
billion to cool, so universe could be around 13-14 billion years old)
c. Cosmic Microwave Background Radiation – most accurate way of dating, should
be around 13.8 +/- 0.04 billion years old
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,Chapter 2: Age and Size of the Universe
1. How do we measure distances in space (2 different units of measure)?
a. Light Years: distance light travels in one year, 300,000 km/s, 8 minutes for light
to travel from Sun to Earth
b. Astronomical Units: Earth to Sun = 1 AU
2. Explain how you can use trigometric parallax to tell the distance of nearby stars
a. Object appears to be in different position based on the viewpoint, star appears to
wobble as Earth rotates around Sun
b. Measure angle of the apparent movement, and distance that Earth has travelled to
find the distance of the star
i. Used for stars up to 500 light years (nearby stars)
c. Can also use Main Sequence Fitting and Cepheids for 500 – 500 million LY
i. Hertzsprung-Russell Diagram, use intrinsic brightness
ii. Cepheids – pulsating stars, use intrinsic brightness to find distance
3. What is our nearest neighbour galaxy as found by Hubble?
a. Andromeda Galaxy
4. What is the Hubble law? Explain the terms? V = Hd
a. Used to find age of universe, but also distance (beyond 500 million LY)
b. Relationship b/w distance of object from Earth and amount of redshift (speed)
c. Use V and H (expansion constant) to find the distance
5. What are the 3 ways to determine distance?
a. Trigometric parallax
b. Main Sequence Fitting/Cepheids
c. Hubble Law
6. Will the Milky Way ever crash with the Andromeda galaxy?
a. Hurdling towards the Milky Way, expected to crash in 3 billion years
Chapter 3: Matter and the Nebular Hypothesis
1. Definitions of atoms, elements, isotopes etc.
a. Atoms: particles of an element
i. Protons, neutrons, electrons (ion: different electron numbers)
b. Element: simplest unit, cannot be broken down further
c. Isotopes: atoms of element, different mass (same number of protons, different
number of neutrons
d. Radioactivity: spontaneous breakdown of unstable isotopes, half-life
2. Define fission and fusion
a. Fission: breakdown of nucleus of heavy isotope into lighter particles, release
energy
2
, b. Fusion: combination of lighter particles into heavier isotope, release energy
3. Formation of elements from light to heavy. Which ones form in the big bang, a star or a
supernova?
a. First 3 elements formed in Big Bang
i. Hydrogen
ii. Helium and Lithium formed from Deuterium (isotope of H) – fusion
b. Nuclear fusion reactions in stars formed elements up to iron
c. Rest of the heavy elements formed by supernovae (more heat and pressure)
4. Describe the nebular hypothesis for the formation of our solar system. Describe what
happens at each stage (collapse, flattening, condensation, growth of planets)
a. Proposes the Solar System formed all at once from a nebula (cloud of gas) – 5
billion years ago
i. Collapse: its self-gravity from all the particles caused contracting
Pocket started contracting from recoil shock wave (supernova)
Pocket increased density, local collapse
Increased collapse increased temperature (particles colliding)
Eventually heat cannot escape, particles collide at high speeds,
enough pressure to stop collapse, heat for fusion reactions and
birth of a star
ii. Flattening: angular momentum (amount of spin)
atom motions add up to make cumulative rotation
cloud spins faster as it contracts, causes flattening
iii. Condensation and Growth of Planets: The Accretion Method
Refractory elements condensed into grains, pebbles, planetesimals,
protoplanets, few planets (material sticking together)
Leftovers would be asteroids, comets
5. Why is the Sun hot?
a. Huge conversion of H into He, large amounts of heat and energy
b. Eventually run out, red giant in 5 billion years
6. Why is the solar system a flat disc?
a. Increased spin of the cloud (as it contracted), flattening
7. Why did all planets originally move in the same direction around the Sun?
a. Cloud had sense of rotation from cumulative motion of atoms, increased spin of
orbiting materials when it contracted
8. The interior planets are made from condensed refractory materials, what happened to the
more volatile gases?
a. Only the center of nebula was hot, temp gradient outwards
b. Temperature gradient caused differing condensation
i. Cooler parts meant everything could condense (even light gases)
ii. Hotter inner parts meant only refractory elements could condense
Volatile – boil off at high temps (H, water vapor)
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