Test 2: Review Sheet

Test: July 5, 2018

1. In what month is the Earth closest to the Sun in its orbit? Farthest from the Sun? At what part of its orbit is the Solar Day the longest? What is the length of the Mean Solar Day? What is the analemma?
2. What are Kepler's 3 Laws of Planetary Motion? Qualitatively, what do each of Kepler's laws tell us? What is an ellipse? How are circles and ellipses related? What is meant by eccentricity? What is meant by semi-major axis? What is meant by semi-minor axis? What is meant by sidereal oribtal period?
3. What was Tycho's most significant contribution to modern astronomy?
4. What were some significant contributions of Aristotle, Aristarchus, and Erastosthenes to astronomy?
5. Compare and contrast the models of Ptolemy (geo-centric) and Copernicus (helio-centric) for the Solar System. Which was favored by the obervations at the time?
6. How was the question of geo-centric vs. helio-centric settled? Outline the issues and the steps followed which allowed us to choose between the two models.
7. What are the dynamical regularities of planetary motions any theory for the origin of the Solar System must explain?
8. What is annual trigonometric parallax? What were the propsed explanations for the lack of observed annual trigonometric parallax?
9. What were the reasons Copernicus's heliocentric theory was not universally embraced?
10. Describe the Copernican explanation for retrograde motion. What the Ptolemaic explanation for retrograde motion? What are morning and evening stars? Which planets will go through a complete cycle of phases (similar to the Moon's phases)?
11. How the force of gravity depend on the masses of the attracting masses and the separation of the masses?
12. Qualitatively, describe how orbital motion works. If the mass of the Sun were to suddenly double, would the orbital speed of the Earth need to increase or decrease to remain in its current orbit? Explain your answer.
13. Describe why the ordering of the contributions of Tycho --> Kepler --> Newton, led to the resolution of the question of the nature of the Solar System (the scientific enterprise that started with the Greeks).

Key:

1-10: c,e,b,e,d,c,c,b,b,d,
11-20: d,a,a,b,a,a,c,d,e,c,
21-30: d,b,d,d,b,b,a,d,d,d,
31-40: d,a,b,a,b,d,b,c,b,c,
41-50: c,c,c,c,e,d,d,b,a,b

1. What are the dynamical regularities and what are the regularities of the planetary properties any viable theory for the origin of our Solar System must explain? What are some minor dynamical regularities any theory for the Solar System must explain? How well do these notions fare in terms of the recent observations of exgra-Solar planets?
2. Compare and contrast the Terrestrial, the Jovian planets, and the rocky/icy planets in terms of their sizes, masses, distances from the Sun, chemical compositions, atmospheres, magnetic fields, densities.
3. What are dwarf planets (what is the definition of dwarf planets)? What was the category of dwarf planets created? What are some members of the class of dwarf planets?
4. How does the condensation theory for the origin of the Solar System account for the dynamical regularities of the Solar System and for the fact that there are three types of planets in our Solar System? Do the dwarf planets fit into this picture? why are the Jovian planets so much more massive than the Terrestrial planets? What is the Snow Line? What is the significance of the Snow Lines for planetary formation? What are refractory elements? What are volatile elements? What did the discovery of planets around a radio pulsar show?
5. What are planetesimals? What are protoplanets? Describe how they fit into the scheme for Solar System formation. What is the current understanding as to why Jupiter/Saturn and Uranus/Neptune are so different?
6. How many extra-solar planets are now known? Roughly how many extra-solar planetary systems have been discovered? In terms of the properties of the newly discovered systems, how does our understanding of the formation mechanisms of planetary systems fare? That is, how do the properites of our Solar System compare to the newly discovered systems? If there are discrepancies, are the discrepancies disqualifying discrepancies or are they perhaps understandable? Explain how you arrive at your conclusions.
7. Are Kepler's laws universal? Is there evidence that Kepler's laws are universal? If so, what is the evidence? Is the Titius-Bode law universal in the same that wwe asked "Are kepler's laws universal?" Answer whether the Titius-Bode law contains physics or is just numerology. Note that this question does not yet have a definitive answer; so your ansuwer is neither right nor wrong, your reasoning is what is important.
8. What are the best current ideads concerning the origin of the asteroids?
9. What are the best current ideads concerning the origin of our Moon?

Sample Multiple Choice Questions

1. A feature of the Jovian planets is that

a. they are composed primarily of methane and ammonia gas
b. they are larger than or around the size of Juptier
* c. they are composed primarily of hydrogen
d. they have relatively hard surfaces of water ice
e. they are all about the mass of Jupiter or larger

3. Which of the following facts must any theory for the formation of
the Solar System explain?

a. the nearly circular orbits of the planets
b. why the Jovian planets are so massive when compared to the
Terrestrials
c. the nearly co-planar orbits of the planets
d. the chemical compositions of the Jovian planets
* e. It should be able to explain all of the above facts

4. Of the following planets, which one's orbital characteristics differs
the most from the other listed planets?

* a. Mercury
b. Earth
c. Uranus
d. Neptune
e. Jupiter

5. Which of the following is a characteristic of the
Terrestrial planets?

a. high density
b. solid outer layers (hard surfaces)
c. small sizes (diameters < diameter of the Earth)
d. they are not very far from the Sun (a < 2 A.U.)
* e. All of the above are charateristics of the Terrestrial planets.

6. The chemical composition of the atmosphere of Mars is
most similar to the atmosphere of

a. Jupiter
* b. Venus
c. the Earth
d. the Moon
e. Mercury

9. The currently accepted theory for the origin of the Moon

a. proposes that the young Earth spun rapidly and ejected the Moon
from its surface
b. proposes that the Moon was formed outside of the Solar System and
was subsequently captured by the Sun
* c. proposes that the young Earth was struck by a Mars-sized object
which led to the formation of the Moon
d. proposes that Earth and Moon formed independently but from one
collapsing gas cloud

10. A key to understanding why there is a large difference between
the masses of the Jovian planets and the Terrestrial planets is

a. that water was able to exist in solid form (ice) only near and
beyond the orbits of the Jovian planets
b. the fact that only in the outer Solar System could forming planets
capture and hold hydrogen and helium
c. rocky material could only be in solid form beyond the orbits of the
Jovian planets
* d. only a and b
e. a, b, and c

11. We expect the Earth's core to be more dense than its crust because

a. in the early stages of the Earth's formation, its interior was molten (or at least, it was soft)
b. the density of material in the crust is less than the overall
average density of the Earth
c. any material becomes more dense as it is compressed by the weight of
the material lying above it
* d. all of the above are correct
e. only a and b are correct

22. The atmospheric pressure of a planet

a. is a measure of the surface temperature on the planet
* b. is a measure of the mass contained in the atmosphere of a planet
c. is a measure of the temperature of the gas around the planet
d. tells you the composition of the atmosphere of the planet

27. Which of the following facts must any theory for the formation of the
Solar System explain?

a. the orbital properties of the Galilean moons of Jupiter
* b. the existence of general classes of planets
c. the origin and properties of the Earth's moon
d. the origin of the atmospheres of the Terrestrial planets
e. Venus rotates in the opposite sense that it revolves about the Sun

28. The Solar System is thought to be

a. 100 - 200 million years old
b. 46 million years old
* c. 4.6 billion years old
d. 10 billion years old
e. 300 - 800 million years old

32. A measurement of the density of a planet can tell us

* a. the rough composition of the planet
b. the age of the planet
c. the mass of the planet
d. the size (diameter) of the planet
e. All of the above can be deduced from only the density of a planet.

39. Of the following planets, which has the largest iron core relative to its
overall mass?

* a. Mercury
b. Venus
c. Earth
d. Moon
e. Mars

42. Terrestrial planets start with different chemical compositions than Jovian
planets because

a. they formed in parts of the Solar Nebula which had radically
different chemical compositions
* b. of the high temperatures in the inner solar nebula
c. Terrestrial planets are smaller than the Jovian planets
d. Jovian planets have stronger magnetic fields
e. Jovian have many moons which altered their atmospheres

15. The Greeks supported the notion that the Earth was stationary in
the center of the Celestial Sphere by

a. simply stating, "that's the way it is, Bud."
b. showing that the stars were much smaller than the Earth.
c. their failure to detect daily changes in star positions.
d. their failure to find other life in the Solar System.
* e. their failure to detect annual shifts in star positions.

32. The assumption that the stars are fixed firmly to the Celestial
Sphre turns out to be reasonable because

a. stars are, in fact, stationary; they do not move
b. stars move very slowly compared to planets; speeds much
less than 1mile per hour
* c. stars are extremely distant
d. stars are fairly nearby
e. stars are optical illusions

34. Which of the following is true about the motions of the planets?

a. They, in general, move west to east through the stars.
b. They move through the Zodiac constellations.
c. They rise in the east and set in the west over the
course of a day.
d. At times, they perform loops on the sky known as
Retrograde motion.
* e. All of the above statements about planets are true.

37. Precession

a. is the accuracy with which numbers are given in astronomy
* b. causes the motion of the Earth's rotation axis on
the Celestial Sphere
c. produces the apparent backward motion of the planets
on the sky
d. causes the daily eastward motion of the Sun
on the Celestial Sphere