NAME ______________________________________________________
Test 2
Astronomy 121
July 3, 2014

20 multiple choice questions each worth 1 point. Select the best answer

1. The discovery of extra-Solar planets _ .

a. has occured primarily over the last twenty years
b. has been going on for the last hundred years; the discoveries were triggered by recent developments in mathematics
c. has taken place slowly but steadily over the last 2,000 years
d. was first made by Galileo and has continued smoothly since then
e. started with Ptolemy, but then stopped until the 18th century when the first large telescopes were constructed

2. Knowing the atmospheric pressures on Venus and the Earth allows one to _.

a. determine the relative chemical make-ups of the two planets
b. determine the depths of the oceans on the two planets
c. determine the escape velocities of the two planets
d. determine the masses of the atmospheres of the two planets
e. determine whether an ozone layer exists around both planets

3. The bulk of the carbon dioxide initially present in the atmosphere of the young Earth _ .

a. has been lost to space
b. is contained in green plants and plankton
c. is tied up in the crust of the Earth
d. is contained in the oceans of the Earth
e. is contained in the polar caps

4. Whether a planet was able to attract and hold onto large amounts of hydrogen and helium when it formed depended strongly on _ .

a. the temperature near it and whether the Sun had turned on
b. the strength of the gravitational pull of the Sun and the planet's moon
c. the chemical composition of the planet's interior
d. whether the hydrogen and helium were actually ices, i.e., in their solid forms
e. the tilt of the spin axis of the planet

5. The ancient Greeks _ .

a. found that the circumference of the Earth was ~25,000 miles
b. correctly surmised that the Earth was spherical in shape
c. deduced that the stars were very distant
d. only A and B are correct
e. A, B, and C are correct

6. In terms of its mass and diameter, _ is considered the Earth's twin.

a. Mercury
b. Venus
c. Mars
d. the Moon
e. Pluto

7. The Greenhouse Effect on the young Venus was ___ .

a. intensified by the presence of technologically advanced life forms
b. weakened by the presence of a thick ozone layer
c. intensified by water vapor
d. intensified by an overabundance of carbon dioxide compared to the Earth
e. very mild because of its thick cloud layer

8. In the Solar System, _ .

a. the planets orbit about the center of the sun
b. the sun orbits about the average positions of the planets
c. the sun actually orbits about the center of jupiter
d. the planets and sun orbit the center-of-mass of the solar system

9. The __ is thought to explain why there is such a large difference between the properties of Jupiter/Saturn and Uranus/Neptune.
a. large amount of water ice in the outer Solar System
b. location of the Snowline in the Solar System
c. the existence of the asteroid belt
d. process which ejected most of the Plutinos in the early Solar System
e. clearing out of the gas of the Solar System by the sudden brightening of the Sun when it first became a star
10. Tycho showed that _ .

a. the Copernican model worked much better than did the Ptolemaic model
b. the Ptolemaic model worked much better than did the Copernican model
c. neither the Ptolemaic nor the Copernican model was consistent with his data
d. the lack of observed annual trigonometric parallax was explained because stars were stationary
e. the sun also underwent episodes of retrograde motion
11. In non-mathematical terms, Kepler's third law says that _ .
a. a planet moves more rapidly in its orbit when near the sun than when far from the sun
b. planets close to the sun have shorter orbitral periods than those farther from the sun
c. the sun is at the focus of planetary orbits
d. slowly moving planets are close to the sun
e. planets move in elliptical shaped orbits
12. The Sun is composed primarily of _ .
a. hydrogen and helium
b. carbon and oxygen
c. helium and oxygen
d. iron and nickel
e. silicon, oxygen, and potassium
13. The precession of the Earth's rotation axis _ .
a. is driven primarily by the slightly non-circular shape of the Earth's orbit about the Sun
b. causes the changing seasons on the Earth
c. is caused by the gravitational force of the Moon on the Earth
d. is a secondary consequence of the Titius-Bode Law
e. explains why there is not a large planet in the asteroid belt.
14. The first great observational astronomer was _ .
a. Aristotle
b. Copernicus
c. Tycho
d. Kepler
e. Newton
15. The heliocentric theory for the Solar system was first proposed _ .
a. in ancient times by Aristotle
b. in ancient times by Aristarchus
c. in medieval times by Newton
d. in medieval times by Copernicus
e. in the the renaissance by Galileo
16. The Titius-Bode law _ .

a. shows that the greater the mass of two objects, the stronger will be the graviational attraction between them
b. explains why Venus and the Earth are so different today
c. made the first prediction of the existence of dark matter in the 1930s
d. predicted the existence of the asteroid belt
e. explains what happened to most of the plutinos in our Solar System

17. In the currently accepted model for planet formation in our Solar System, __ .
a. dust coalesces to form planetesimals which then capture objects gravitationally to form protoplanets
b. jupiter always forms outside the snowline of the system
c. rock, iron, helium, or combinations of them make up most of jupiter d. only a and b are correct
e. a, b, and c are all correct
18. What important event occurred while the sun was in its T Tauri phase (the phase when the young Sun developed an intense solar wind)?
a. Jupiter was formed
b. the Earth-Moon system was formed
c. the Sun ran out of fuel and started to fade
d. the gas remaining in the Solar System was blown out
19. The density of the Moon is most similar to _ .
a. the density of the Sun
b. the average density of Jupiter
c. the density at the center of the Earth
d. the density of the rocks in the crust of the Earth
e. the density of Saturn
20. 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

Short Answer Questions--5 questions each worth 4 points.
1. Compare how the models of Ptolemy (geo-centric) and Copernicus (helio-centric) explained retrograde motion. Which was favored by the observations of their times?
2. List the primary dynamical regularities of the planets any viable theory for the origin of our Solar System must explain. What are the secondary dynamical properties which must be considered?
3. Compare and contrast the Terrestrial and Jovian planets in terms of their sizes, masses, distances from the Sun, chemical compositions, atmospheres, densities.
4. Describe how the condensation theory for the origin of the Solar System accounts for the dynamical regularities of the Solar System and for the different types of planets of our Solar System. How do dwarf planets fit into this picture?
5. List and state Kepler's three laws of Planetary Motion.